Bill Spencer, Jr. is the previously unknown son of publishing magnate Bill Spencer, Sr. They had never been close, but when the elder Spencer died, Bill came to Los Angeles to carry out his father's last wish: to avenge his one true love, Stephanie Forrester, by destroying Eric Forrester and Forrester Creations. Bill encouraged Stephanie, who had defected to rival fashion house Jackie M, to rant about the Logans in a damaging video blog. Eric refused to sell Forrester to Bill, who blackmailed Eric with the knowledge that Eric had hired an illegal immigrant years ago. But Stephanie recorded the conversation and threatened to go public unless Bill backed off.
A consummate womanizer, Bill put the moves on an unresponsive Donna Logan. Later, Bill met Donna's sister, Katie Logan. Fresh from a breakup with Nick Marone, Katie got drunk at the Cafe Russe, but Bill chose not to take advantage of her. Instead, Bill got to know Katie, who challenged Bill's tendency to be a shark. When Katie found the DVD of Bill's father laying out his mission to Bill, Katie questioned Bill's growing feelings. But Bill insisted his devotion was genuine, and proposed. Bill knew Katie wanted to do something special after a second chance at life via a heart transplant, so when Bill finally secured Forrester Creations, he made Katie its CEO.
Young Steffy Forrester was intrigued by Bill and kissed him. But Bill still married Katie in her old San Fernando Valley neighborhood. Resenting Bill's control of their company, the Forresters unsuccessfully tried to sabotage Bill by creating the ugly Dare fashion line. Steffy took things one step further and used Bill's attraction to set up a seduction. Bill bit, but Steffy put on the brakes and stole Katie's engagement ring from Bill's bedroom. Steffy threatened to show it to Katie if Bill didn't sign Forrester over to Steffy. Bill fumed and vowed revenge, but secretly admired Steffy's ruthless behavior.
Bill befriended Donna, whose marriage to Eric was in trouble, and suggested Donna ask for half of Eric's Forrester stock in the event of a divorce. Bill began to think of the Logans as the family he never had, offering to join forces with Stephen Logan against Eric and blasting his right-hand man, Justin Barber, for exposing Brooke's "mistaken identity" sex to the world. But later, Bill had no problem exposing Brooke's daughter, Bridget, when she had her own paternity scandal, saying he'd already given the Logans "a free pass." Bill also convinced Donna to sell him the 12.5% of Forrester she'd gotten from Eric, and tried to buy an additional 25% from Steffy.
Liam Cooper, an intern at Spencer Publications, revealed that his mother, Kelly Cooper, had died and sent him to Los Angeles in search of his father. Kelly had dated both Bill and Thorne Forrester, who insisted on a DNA test. Bill scoffed to find he had a son in the forthright Liam, but Katie encouraged Bill to develop their father-son bond. Bill wanted Liam to man up and disapproved of Liam dating the gentle Hope Logan, so Bill tried to press Hope's ex-boyfriend, Oliver Jones, into winning Hope back. Failing that, Bill arranged a coming-out party and introduced Liam to the press as "the world's most eligible bachelor," which made Liam uncomfortable. Bill backed off and accepted Hope.
Bill went ballistic when Amber Moore claimed that Liam was the father of her baby. After Amber's mother, Tawny Moore, managed to fix the paternity test, Bill offered Amber $500,000 to leave town. But Amber wanted more, so Bill bought a cliff house that had a faulty balcony and moved Amber in, hoping Amber would fall to her death. Steffy returned from working in Europe determined to have Bill for herself, and caught Bill luring Amber to the edge. A tree branch fell, almost doing the job for him, but Steffy saved Amber. Katie walked out when she discovered Bill's plot, but Steffy told Bill she "got" him and was better for him than Katie, who demanded Bill seek therapy.
Bill snarked his way through sessions with Steffy's mother, Dr. Taylor Hayes and seemingly made up with Katie off-screen.. But when Steffy's brother, Thomas, went missing at sea, Steffy begged Bill for help. After Bill used his resources at Spencer to rescue Thomas, he reciprocated Steffy's declaration of love. Steffy had family problems and leaned on Bill for support, igniting a full-blown affair. Taylor caught them before they could make love and kicked Bill out of the house. Bill was ready to leave Katie, who surprised him with a vow renewal ceremony. But Katie had a heart attack when Taylor told her about the affair, and Bill chose to stay with Katie. Steffy was devastated, but fell for Liam after he saved her from drowning in her bathtub.
Steffy's father, Ridge Forrester, punched Bill over his involvement with Steffy, so Bill went to Nick with an offer to buy 50% of Jackie M in order to crush Forrester. Nick was tempted, but Nick's mother, Jackie Marone, ultimately nixed the deal. Bill again deemed Hope unsuitable for Liam, so he teamed with Steffy to get rid of Hope. On Bill's orders, Steffy kissed Liam at Liam's bachelor party. Hope saw it and left her engagement ring on Liam's mantel. Liam offered the ring to Steffy, and Bill capitalized on it by sending Steffy and Liam to Aspen. When Hope followed, Bill arranged a wedding for Steffy and Liam, which Hope was forced to watch while trapped in a gondola, courtesy of Bill.
Katie was outraged when Bill gave Steffy a seat on the Spencer board and planned a "family vacation" to Cabo San Lucas. Bill stayed behind, helping from the sidelines when Hope and Thomas ended up at the same resort as Steffy and Liam. But Hope and Liam saw each other, and Steffy was injured in an ATV accident. Knowing that Liam wanted to return to Hope, Bill fixed Steffy's MRI to say she had a life-threatening blood clot that could worsen under stress. Liam felt obligated to stay with Steffy. Katie got suspicious, and soon uncovered Bill's plot. Bill locked Katie in a tower to keep her from exposing him, but when she escaped and told Liam, Bill found himself alone. Hope threatened to go public with Bill's crime, yet never made good on the threat. Bill and Katie again resolved their issues off-screen, though one night Bill fantasized about Brooke during dinner.
Bill raised an eyebrow when his half-sister, Karen Spencer, relocated to Los Angeles with not only her daughter, Caroline Spencer, but a friend, Danielle. Bill assumed that Danielle was Karen's roommate, but soon learned that Danielle was Karen's spouse. Karen explained she had kept her sexual orientation a secret because she feared Bill's reaction, but Bill accepted both Karen and Danielle. However, he continued to persecute Hope, who had reunited with a separated Liam but began taking antianxiety medication because the press labeled her an adulteress. Bill sicced the paparazzi on Hope, then bribed a warden to spring Hope's father, Deacon Sharpe, from jail as part of a plan to prevent Liam's wedding to Hope in Italy.
When Katie told Bill she was pregnant, Bill insisted she get an abortion. Bill later softened and admitted he was only afraid Katie would die trying to carry a baby to term given her heart condition. Later, Katie found Deacon in Bill's office, and the truth about Bill's misdeeds triggered Katie to go into an early labor and flatline on the operating table. Katie recovered, but couldn't forgive Bill for breaking the law; Bill only avoided prosecution because Katie and her sisters wanted to protect Katie's baby, Will. Bill threatened to have Deacon killed when Deacon tried to blackmail Bill into giving him a job at Spencer.
Katie slid into postpartum depression and disappeared, so Bill and Brooke teamed up to find her on a wild goose chase to Aspen, only finding a note from Katie asking for a divorce; Bill didn't know that Katie thought she didn't have long to live and wanted Brooke to replace her in his life. Brooke opened up to Bill about having lost Ridge to divorce and Stephanie to cancer, which led Bill and Brooke to kiss. Returning home, Bill was surprised that Katie had recuperated and wanted her life back. Taylor heard about Bill kissing Brooke and told Katie; Bill swore it meant nothing.
Later, Bill stood accused of pushing Caroline over a balcony after arguing with her about how he used Deacon to sabotage Hope's wedding, which Hope still knew nothing about. When Hope found out, she literally crashed an intervention Katie had set up to deal with Bill's drinking by bashing her way through Bill's window with a golf club. Liam turned his back on Bill, who stabbed himself in the chest with his trademark sword necklace to engender sympathy, secretly taping his money pouch under his shirt to cushion the blow.
His marriage to Katie increasingly strained, Bill continued to think of Brooke, and encouraged her to reboot her once successful Brooke's Bedroom lingerie line. After a successful pitch, Bill and Brooke celebrated with champagne, which Taylor relayed to Katie. Bill told his furious wife that he was sick of her “rules and regulations”, but later drove drunk to go home and make things right with her, swerving into Brooke's car. Bill and Brooke kept the accident from Katie -- and the police -- but when Katie stopped by and saw Bill in Brooke's bed, she took off her ring and demanded a divorce. Bill and Brooke felt free to finally make love, but their afterglow was interrupted by new that Katie had suffered heart failure. When Katie awoke from her coma, she asked Bill to come home, so Bill tried to make it work with her.
Bill was happy to see Liam marrying Steffy, but when Steffy was in a motorcycle accident and miscarried their baby, Bill encouraged Liam to direct his anger at him instead of his wife. Meanwhile, Bill intervened when Caroline reported that her beau, Rick Forrester, had eyes for Maya Avant; Bill learned that Maya had been wrongly convicted of a crime because of her ex-boyfriend, Jesse Graves, and that she could go back to jail if she came within 500 feet of him. Bill sent Jesse to a club where Maya was and had his assistant, Alison, snap a photo of them. Maya refused to be blackmailed and told Rick, who locked Bill in a mock jail cell used for a photo shoot to teach him a lesson.
Brooke had important news for Bill and Katie, but fainted before she could say anything. Brooke brushed it off as stress, but privately told Bill she had just miscarried his child. Bill and Brooke covered their sadness at the birthday party Katie threw for Brooke, but Taylor found out the truth and exposed their affair in front of all the guests! Katie slapped Bill and threw him out; later, Bill agreed to Katie's request for 1% of Spencer Publications in their divorce settlement. But Bill was stunned when Katie combined her stock with Karen's; now the majority stockholder, Karen made Katie CEO, then fired Bill and had him removed by security guards.
Bill received another shock when it turned out that new arrival Wyatt Fuller was another long-lost son, this time from a short fling with jewelry designer Quinn Fuller. Bill was amused by Wyatt and Liam's instant sibling rivalry over Hope, but, when Wyatt judged Bill for his affair with Brooke, Bill kicked Wyatt out of the family until Brooke played peacemaker between them.
Katie allowed Brooke to babysit for Will; Bill and Brooke took this as a sign that Katie was forgiving them, and they discussed the baby that they had lost. But Bill discovered that Katie had set up hidden cameras to test him and Brooke, then followed Brooke to Monte Carlo, where she was promoting Brooke's Bedroom. Brooke ran when Bill said he wanted a life with her; he chased her through Monte Carlo and convinced Brooke to give their relationship a chance. When Bill and Brooke returned to Los Angeles, they moved in together. Soon, Bill told Brooke he wanted to marry her as soon as his divorce was final.
Bill clashed with Katie in the Spencer board room, and on the home front, as she refused to let Will visit him at Brooke's. While mountain climbing in Aspen, Bill nearly fell to his death; having had an epiphany, Bill reconciled with Katie and made love to her. Bill then convinced Katie to sign papers returning control of Spencer Publications to him and establishing joint custody of Will. Bill ran to Brooke with the documents, bragging how he had tricked Katie so he could have his company, his son, and Brooke. But Bill was surprised when Brooke replaced the papers with leaves from Aspen and threw him out. Bill moved back in with Liam, swearing Brooke would be his again.
Liam asked Bill to talk to Wyatt about moving in on Hope; when Quinn found out, she drew blood from Bill with his sword necklace and licked it from her finger. Bill's hopes for a reunion with Brooke were quashed when Ridge returned to town after a year in Paris, wanting Brooke back for himself. But when Ridge learned of Brooke's affair with Bill and backed off because of how it hurt Katie, Bill used photos he dug up of Ridge at a gay pride parade to convince Brooke that Ridge was gay. It didn't work, and, when Ridge finally proposed to Brooke, Bill got drunk the day of the wedding and had raucous, S&M sex with Quinn. Katie, who had developed feelings for Ridge, stopped the ceremony by fainting on purpose, but Brooke wouldn't take Bill back; he found Quinn in his bedroom ready for more whips and chains, but Brooke returned to talk to Bill, so he stashed Quinn in the closet and told her to keep quiet. Although Brooke wanted more time to reconsider her relationship with Bill, the two soon reunited and moved in together.
Bill was unhappy to hear that Spencer Publications was faltering under Katie's leadership; after Karen refused to reinstate him, Brooke surprised Bill by revealing that she had saved the papers he tricked Katie into signing, and that she had used the documents to force Katie to step down. Bill proudly reclaimed his CEO chair, but ran into problems when Quinn showed Bill a photo she had taken of them in bed and manipulated Bill into officially making Wyatt a Spencer. Bill gave R.J., Brooke's son with Ridge, a Spencer family sword necklace, after which Ridge and Bill got into a fistfight over Bill's influence on R.J.Bill proposed to Brooke and planned a wedding trip to the United Arab Emirates, where Bill took Brooke on a tour of Dubai and Abu Dhabi. Unbeknownst to Bill, Quinn showed Ridge the selfie of herself in bed with Bill, and Bill was shocked when Ridge showed up during his wedding to show the photo to Brooke. As Bill explained himself, Ridge punched him and dragged Brooke away and into a helicopter -- which was actually being piloted by Justin. Bill ordered Justin to “cool him off,” so Justin banked the chopper, and Ridge fell into the Persian Gulf. With both Brooke and Katie desperate to find the missing Ridge, Bill organized a search team and secretly insisted to Justin that all he wanted to do was teach Ridge a lesson, not hurt him. Eventually, Brooke found Ridge wandering on the beach, but his memory was impaired due to a concussion, which brought Bill relief since Justin said Ridge probably noticed the Spencer logo on his jacket. Once home, Bill told Quinn he wanted nothing more to do with her for her part in influencing Ridge to ruin his wedding.