June 7, 1989; December 22, 1989;

May 21, 1990 to May 24, 1990;

January 3, 1991 to January 8, 1991

September 6, 1994 to October 4, 1994; November 16, 1994; December 12, 1994;

February 21, 1995; April 12, 1995; November 29, 1995;

January 26, 1996 to February 6, 1996; March 27, 1996 to April 2, 1996;

March 27, 1996 to April 3, 1997;

May 27, 1997 to June 10, 1997; August 28, 1997;

December 18, 1997 to January 7, 1998;

October 19, 1999 to November 15, 1999

February 1, 2000 to February 2, 2000; April 10, 2000;

January 12, 2001 to January 17, 2001;

April 30, 2003 to May 8, 2003;

May 28, 2004 to June 1, 2004 [guest appearances]

The youngest child of Stephen and Beth Logan, teenaged Katie felt as if she were in the shadow of older sisters Brooke and Donna Logan, which, along with a bad case of acne, made her feel insecure. Katie brightened when Rocco Carner asked her out; Katie considered Rocco her boyfriend and couldn't see that Rocco was more interested in Donna. Katie was furious when she caught Donna and Rocco kissing. Katie forgave them, but Rocco wanted to marry Donna, and put an engagement ring in Katie's coat pocket, thinking the coat was Donna's. Katie found the ring and assumed it was for her. Katie was hurt despite Rocco letting her down easy, but soon she was able to move on with Kurt, a college classmate.

Katie was thrilled when an "anonymous" tip (really dropped by Stephanie Forrester, who wanted to lure Beth away from her husband, Eric Forrester) indicated that Stephen, who had walked out on the Logans years before, was in Arizona. After her parents reconciled and moved to Paris, Katie faded into the background for years, occasionally seen working at the Insomnia Café or when Brooke needed a babysitter.

In 2007, Katie arrived for Donna's wedding to Thorne Forrester. But Katie overheard Donna admitting she was only marrying Thorne to get back at Stephanie for hurting Brooke; Katie went to Thorne, and the wedding was called off. Having become skilled in public relations, Katie decided to stay in Los Angeles when Forrester Creations offered her a position.

Katie's brother, Storm Logan, shot Stephanie and framed Stephen for the crime. After it was discovered that Storm pulled the trigger, Katie convinced Stephanie not to press charges. But when the unstable Storm took a gun to the home of Ashley Abbott, who had broken up with him, Katie followed him there, and Storm's gun went off in the struggle. Critically wounded and in need of a heart transplant, Katie was devastated when Storm shot himself in order to donate his heart to her. But when Katie's body rejected Storm's heart, her doctor niece, Bridget Forrester, worked on possible treatments.

A dying Katie was moved when Bridget and her fiancé Nick Marone threw her the high school prom she never had; alone with Nick on Catalina Island, Katie fell in love with him. Once Katie recovered, she officiated at Nick and Bridget's wedding; soon it was revealed that Katie had made love to Nick off-screen as a dying wish, and the encounter left her pregnant. Katie and Nick prepared for their baby after Bridget walked out, but Katie miscarried. After briefly fixating on Nick's son, Jack, Katie bounced back in time for her wedding to Nick, where Nick's mother, Jackie Marone, joined Bridget in making Katie feel so bad for betraying Bridget that Katie postponed the ceremony.

Seeing that Nick was still drawn to Bridget, Katie got drunk and met womanizer Bill Spencer, Jr. Katie appreciated that Bill didn't take advantage of her in her impaired state. Katie and Bill began to date, and Katie was touched when the ruthless tycoon admitted no one else had gotten past his armor. But one day Katie found a DVD left by his late father, Bill Spencer, Sr. which instructed Bill to avenge him by taking over Forrester Creations. When Katie questioned Bill's reasons for seeing her, he declared his love and his intention to give survivor Katie a chance to do something important. Katie was floored when Bill proposed to her, then took over Forrester and made Katie its CEO. With her parents at her side, Katie joyfully married Bill in her old neighborhood of Sherman Oaks.

Katie struggled to keep the peace when she put Donna and Brooke in the leadership positions the Forrester men refused. Katie stepped down when Bill suddenly returned the company to the Forresters; she never found out that Bill had only done so because the young Steffy Forrester had blackmailed him over his attraction to her. When Bill discovered that Liam Cooper was his son, Katie encouraged a father-son relationship between them, but soon saw a darker side to Bill when he plotted to kill Amber Moore, who claimed Liam was her baby's father. Detesting violence because of what happened with Storm, Katie walked out and refused to return until Bill agreed to therapy with psychiatrist Taylor Hayes.

Seemingly working out their problems off-screen, Katie surprised Bill with a vow renewal ceremony, only to find out that Bill intended to leave her for Steffy. Katie had a heart attack; from her hospital bed, Katie demanded that Bill choose between her and Steffy. Katie kept her husband but fumed when Bill gave Steffy a seat on the Spencer board, and chafed when Steffy, who had since fallen in love with Liam, was included during a family vacation to Cabo San Lucas. Katie discovered that the seemingly life-threatening blood clot Steffy sustained during an ATV accident was a lie engineered by Bill, who faked Steffy's MRI to keep Liam from returning to his first love, Katie's niece Hope Logan. Katie found herself locked in a tower by Bill when she tried to tell Liam the truth. Katie escaped and turned her back on Bill, though the Spencers once again resolved things off-screen.

Katie risked a pregnancy given her heart condition, despite Bill pleading with her to have an abortion. When Katie heard that Bill sprung Hope's father, Deacon Sharpe, from jail to stop Liam's wedding to Hope, Katie went into premature labor and had a near-death experience in which she saw Storm. Afraid she'd eventually leave baby Will motherless, Katie slid into postpartum depression and took off, trying to draw Bill and Brooke together so Will would have parents. Katie recovered with the help of Taylor and Donna, but by then Katie noticed an attraction had developed between her husband and sister.

Katie forgave Bill and Brooke for kissing, but took off her wedding ring when she caught Bill in Brooke's bed recovering from a drunk-driving accident they'd kept from her. Katie, who had been neglecting to take her anti-rejection medication, went into heart failure and briefly lapsed into a coma. Katie took Bill back anyway, then became an unlikely confidante to former rival Steffy, who had miscarried Liam's baby. Later, at Brooke's birthday party, Katie raged when Taylor arrived with proof that Bill and Brooke had been having a full-blown affair. Katie asked for 1% of Spencer Publications in a divorce settlement, then gave it to Bill's sister, Karen Spencer, who owned 50%, making Karen the majority stockholder; Karen made Katie CEO of the company and fired Bill.

Katie tasked Brooke with babysitting Will, installing hidden cameras to ensure that Bill and Brooke behaved. Vulnerable after Bill nearly fell to his death mountain climbing in Aspen, Katie allowed herself to be seduced by Bill and signed papers returning control of Spencer to him. Katie steamed when she learned Bill tricked her, but was impressed when Brooke replaced Bill's papers with a pile of leaves. Later, with the company faltering under Katie's leadership, she was forced to relinquish it to Bill when Brooke produced the papers she had supposedly burned.

Katie fell for Brooke's on-again-off-again love, Ridge Forrester, after commiserating with him about Brooke's affair with Bill. With Ridge poised to reunite with Brooke, Katie pretended to faint to stop their wedding, then confessed her feelings. Though Katie's relationship with Ridge drew opposition from both their families, Katie accepted Ridge's proposal. However, Katie was horrified when Ridge flew to Abu Dhabi to keep Brooke from marrying Bill only to go missing after falling out of a helicopter into the Persian Gulf. Katie joined Eric and Thorne in the search, overjoyed to find Ridge, who survived with an impaired memory. When Ridge held Bill to blame, Katie investigated with Deacon and learned that Bill's helicopter had indeed been in Abu Dhabi that day, forcing Bill to confess.

Katie kept Ridge's confidence when his brain damage left him unable to design but didn't like it when it turned out he was able to draw by guiding the hand of fledgling designer Caroline Spencer. Learning Ridge and Caroline had kissed, Katie reported it to Bill, smiling to Will that "Daddy would take care of it." When Ridge came home bloodied by Bill, Katie told Ridge she wanted all of him, but ultimately called off their engagement. Katie resisted overtures from Bill, who made Katie a vice president at Spencer. Moving past her misgivings, Katie remarried Bill and reached out to Brooke, who made drunken asides during the ceremony. Katie supported Brooke as she went into Alcoholics Anonymous. Later, Katie was disgusted when Bill published an exposé on transgender model Maya Avant in an attempt to have Maya's boyfriend, a tyrannical Rick Forrester, removed from Forrester's CEO chair.

Katie was on hand to support Liam's half-brother, Wyatt Spencer, who wanted to start a new fashion house that Bill refused to bankroll, and Ridge, who was conflicted over having a baby with Caroline. Seeing that recovering alcoholic Brooke spent too much time alone, Katie offered her sister a job at Spencer Publications. But when Katie overheard Brooke telling Bill he'd always be the love of her life, Katie descended into insecurity and paranoia to the point she began drinking herself. Though Bill and Brooke swore nothing was happening between them, Katie continued accusing them and hid bottles in the kitchen despite a session with her therapist, Dr. Hayden, during which Katie confessed she'd stopped taking her antidepressants.

Katie got caught in a cycle of swearing off booze then drinking more heavily. Indulging at a restaurant, Katie saw Ridge in heavy conversation with Dr. Wolin, a fertility specialist who told Katie that Caroline's baby, Douglas Forrester, couldn't be Ridge's. Katie got Caroline to slip that Ridge's older son Thomas Forrester was really Douglas' father; Katie shared the news with Bill but was furious he passed it along to Brooke; Katie told Bill and Brooke to be together, then apologized for her overreaction. Katie worried she was imagining everything until Brooke confirmed she and Bill had resumed their affair.

When Bill hid Will away, claiming Katie was an unstable parent, Katie was impressed with the way Brooke convinced Bill to return Will to her. Katie stopped drinking and agreed to an amicable divorce, but couldn't persuade Bill to give her his 12.5% stake in Forrester, which Ridge wanted to stop Quinn Fuller, an unstable woman prone to criminal activity that Eric had gotten involved with. Finally feeling stronger, Katie signed Bill's divorce papers and released him to be with Brooke. Wanting a fresh start, Katie bought a house next to Eric, who had helped Katie get Will into an exclusive school. Katie was taken aback when Quinn, now married to Eric, announced she didn't want Katie visiting Eric unattended. Katie came to disbelieve Quinn's claims that Eric's love had rehabilitated her and had trouble denying she had developed a crush on Eric when Brooke questioned her about it.

Katie caught Ridge, who was set to remarry Brooke, in more than one overly-affectionate clinch with Quinn and felt frustrated when Brooke wouldn't heed her warnings. Learning that Ridge and Quinn had been kissing on the sly, Katie agreed to keep Eric in the dark but taunted Quinn and forced her to put her on Forrester's jewelry design team. When Quinn fired Katie for her lackluster product, Katie grabbed security guard Charlie Webber's errant but empty gun and aimed it at Quinn. Katie was questioned by police when someone shot at Quinn several times, but it was Katie who discovered that Deacon was the culprit, having seen Deacon threatening Quinn through her telescope; Katie called Ridge, which saved Quinn's life. Later, Katie was shocked to discover Eric's felonious ex-wife, Sheila Carter, in her house asking Katie to speak to the Forresters on her behalf; Katie doubted Sheila's claim that she had emerged from prison rehabilitated.

Rehired to do PR at Forrester, and not having worked in that field since the advent of social media, Katie sought advice from PR guru and former stepson Wyatt. Over the course of creating a Forrester/Spectra fashion duel in Monte Carlo, sparks flew between Katie and Wyatt, but Katie was gunshy because of their connections to Bill and Quinn, so Katie attempted to set Wyatt up with an infatuated intern. Katie was won over by Wyatt's earnest insistence and agreed to a secret no-strings relationship with him, only to be dragged out of bed by an angry Quinn. Katie let Thorne kiss her and considered moving on with him when Wyatt suddenly dumped her, but when Wyatt finally professed his love, Katie agreed to be Wyatt's wife.

Katie was furious when Bill threatened to disown Wyatt and take custody of Will if Katie married Wyatt. After Katie found Bill lying in a pool of blood from a gunshot wound, Katie supported him in his recovery but decided to keep her continuing engagement to Wyatt a secret, since Bill had offered to make Wyatt CEO of Spencer in five years if Wyatt broke things off with Katie. When Wyatt lamented being cut off by Bill after Wyatt ratted Bill out to Liam for faking an ongoing affair with Steffy, Katie half-jokingly assured Wyatt she had enough money from Bill's divorce settlement to support him. But, seeing Will confused over Wyatt's role in his life, Katie ended things with Wyatt and let Thorne pursue her. Katie and Thorne hired an IT specialist when someone began posting threatening messages on the Hope for the Future web site.

Feeling Bill had neglected Will during his pursuit of Steffy, Katie took Thorne's advice and filed for sole custody of the boy, marrying Thorne just before the hearing. After she was awarded full custody, Katie was shocked to learn that Ridge had influenced the judge in Katie's favor. Trying to compensate for Ridge's involvement, Katie let Bill spend more time with their son but faced Bill's wrath when he discovered she was complicit in keeping secret what Ridge had done. Katie was surprised when Bill let everyone off the hook, and agreed to restore Bill's joint custody, feeling that perhaps Bill's claim of being a changed man was true.

At Will's behest, Katie began spending more time with him and Bill as a family, including Thorne but not noticing his discomfort. Katie's jaw dropped when Thorne announced he was leaving her because he sensed Katie still had feelings for Bill. Katie insisted she only wanted Bill as a co-parent for Will, yet she couldn't help being moved after she ended up on repeated dates with Bill thanks to a mystery matchmaker. Katie found out Will had snagged Bill's credit card to pay for the expensive dinners and was more amused than annoyed. However, when Bill suddenly proposed, Katie declined, not sure she could really trust Bill romantically again.

Katie received a shock when she learned Storm had had a secret daughter, Florence Fulton, whom Storm had not been aware of during his lifetime. Katie and her sisters embraced Flo, but Katie had a change of heart about Bill's proposal upon finding him in heavy conversation with Flo's mother, Shauna Fulton. Learning that Shauna had once had a brief involvement with Bill, Katie recruited Shauna to try and seduce Bill. Katie was amazed when Bill rejected Shauna and declared his love for her; Katie and Bill happily told Will that they were reuniting.

Katie reeled to learn Flo had been part of a cover-up started by Reese Buckingham, an obstetrician who stole Hope's baby, switched it with a dead one, and used money from its adoption to pay gambling debts. Later, Katie began to feel sick and was soon hospitalized with kidney failure, the result of taking anti-rejection medication for years. When none of her family members were a suitable match for kidney donation, Katie was sure she was going to die until an anonymous donor came through at the last minute. Katie was shocked to learn her donor was Flo; because both her heart and now her kidney had been a part of Storm, Katie expressed her gratitude to Flo and was inclined to forgive her for the heartache she brought to Hope and the family.

After recovering, Katie ran into Wyatt's on-again-off-again girlfriend Sally Spectra during a follow-up at the hospital and supported her when she learned Sally was dying from a terminal illness. Katie told Sally she'd keep the diagnosis a secret but went to straight to Bill and Wyatt, then to Ridge and Steffy when she learned the co-CEOs had been displeased with Sally's work. Katie deflected when Sally, who'd been invited to move in with Wyatt and whose designs suddenly found their way into Forrester's couture line, suspected that Katie had tipped people off about having a month to live.

At a reunion party for Ridge and Brooke, Katie saw a video of Brooke kissing Bill on a digital picture frame. Katie listened to Bill and Brooke's vehement insistence that the kiss had been a one-time thing but decided to live apart from Bill; Katie was sure she would work things out with her sister eventually, but couldn't be as certain she could trust Bill again. Katie cordially but firmly rejected Bill's repeated attempts to reunite.

Katie felt furious and betrayed after discovering that Sally had been lying about being terminally ill so she could win Wyatt back from Flo. Then, Katie learned that Ridge's drunken marriage to Shauna in Las Vegas had been orchestrated by Quinn and rushed to tell Ridge the news. And, despite spending several months deliberating, Katie still couldn't decide whether to take Bill back, even when Brooke and Donna teamed up to convince her to do so.

Katie led the charge when Wyatt asked her, Brooke, and Donna to finally forgive Flo for her part in Beth's illegal adoption. Katie hired Flo to work alongside her in PR at Forrester, then joined her sisters in allowing Flo to take the Logan name. Later, Katie struggled to deal with the ramifications of Bill being jailed for covering up a hit-and-run accident Liam was involved in, along with counseling Donna as she continued to pine for Eric. Katie also lent Eric an ear, learning that he was struggling with erectile dysfunction and that he had opened up his marriage so that Quinn could get her sexual needs met by her lover, Forrester COO Carter Walton. Katie wound up commiserating with Carter after Quinn and Eric reestablished their exclusivity, as Katie continued to rebuff Bill's attempts at reconciliation, wanting a man who would love only her. Katie seemed to be getting close to Carter, but drifted away from him over family time with Will and Bill and not completely closing the door on a reunion with Bill.

Eventually, Katie realized any romantic relationship with Bill wouldn't work because of his lingering feelings for Brooke. When Katie found out that the now-single Quinn had moved out on Carter, Katie impulsively kissed him. Things began to develop between Katie and Carter when he accompanied her to a yearly heart exam and presented her with a heart charm to celebrate her clean bill of health. Not long after Katie rejected Bill's latest attempt at a reunion, Katie was horrified to learn that Bill had become romantically involved with Sheila, who, among other things, had shot Steffy. Katie became confused when she couldn't talk any sense into Bill and when she learned that Steffy and her husband, John "Finn" Finnegan, another victim of Sheila's, had refused to testify against Sheila. Demanding answers, Katie reeled when Taylor admitted that she had been the one to shoot Bill years earlier, and that Bill was using Taylor's freedom as a bargaining chip for Sheila's.

Her emotions running high when Bill revealed that his romance with Sheila had only been a ruse to get her to confess to a long-ago murder, Katie slapped Bill, then kissed him. Although Bill took that as encouragement and resumed his pursuit of her, Katie staved off Bill's advances in favor of her growing relationship with Carter.