Kidnapped Laura Spencer [1983; never brought up on charges]
Raped Laura Spencer 
Locked Helena in a room [Jun 21, 2001]
Possessed bio-toxin [Jun 22, 2001]
Used "Lucien Cain" as an alias while out in public [Jun 27, 2001]
Hit Luke Spencer over the head [Jul 23, 2001]
Murder; along with Helena, they used a man to test the virus and, in the process, he died [Jul 24, 2001]
Impersonated a monk [Aug 30, 2001]
Murdered Chloe Morgan [Sep 4, 2001]
Let Stefan Cassadine be accused of committing Chloe's murder [Sep 4, 2001]
Attempted to kill Lucky Spencer by throwing him into the river bound and gagged [Oct 5, 2001]
Tied Stefan up [Oct 16, 2001]
Attempted to stab Luke Spencer [Nov 9, 2001]
Hit Nikolas Cassadine over the head and rendered him unconscious [sometime between Jan and Apr 2013]
Kidnapped Lulu Spencer [Mar 21, 2013]
Clobbered Dante Falconeri over the head and rendered him unconscious [Mar 21, 2013]
Shot Nikolas Cassadine in the chest [Mar 21, 2013]
Held Luke Spencer and Laura Webber hostage on Cassadine Island [Apr 10, 2013]
Arranged for Lulu Falconeri to be injected with a tranquilizer and fertility hormones [Sep 15, 2014]
Attacked Dante Falconeri and held Lulu Falconeri at knifepoint [Sep 16, 2014]
Stavros was the real heir to the Cassadine throne. Being a prince, he was raised as a spoiled brat who got everything he wanted. This eventually led him to kidnapping Laura Spencer, whom he was completely obsessed with. He lied to her and told her that her husband, Luke, was dead. He took her to an island, where he forced him to marry him. He raped her and impregnated her with his son, Nikolas Cassadine.
Stavros' mother, Helena, was very jealous of her precious boy's obsession with Laura. The evil Cassadine mother helped Laura escape from the island. This led Stavros to find her with Luke. After a long fight, Luke and Laura watched as Stavros fell down a flight of stairs after catching his foot on a step, and Helena always swore that Luke killed her son. He broke his neck, and Luke and Laura watched their enemy "die."
Twenty years later, it was revealed that Helena had had Stavros' body cryogenically frozen. She kept him frozen until technology allowed him to be revived. After being thawed out, Stavros quickly began wreaking havoc on Port Charles. Nobody knew he was alive, but he would go to Laura's house and place things and clues there that would remind her of him. He would also secretly tantalize his brother, Stefan.
Stavros met Chloe, who was very close to Stefan. Pretending he was Lucien Cain, a successful businessman, he tried to play Chloe against Stefan. Chloe eventually figured out exactly who Stavros was. Unfortunately for her, though, before she could tell Stefan, Stavros murdered her and set Stefan up to take the rap.
Stavros, or "Lucien," also became involved with his son's ex-girlfriend, Gia. He tried getting close to her to obtain information about his son. Working with Helena, he tried to figure out whether Nikolas was on the Cassadines' side or if he was faking.
Stefan and Laura figured out that Stavros was alive. Stefan escaped from jail, and the two brothers encountered each other at Wyndemere. Surprisingly, Stefan, tied his brother up and left him in a coffin. When the police arrived looking for Stefan, they found Stavros in the coffin and, after questioning, let him go.
When Helena was ready for Stavros to meet Nikolas, she had Stavros pretend he was still frozen. They wanted to see how Nikolas reacted when he saw his father. While Stavros and Nikolas were alone together, Nikolas looked at his "frozen" father and said he hated Stavros and never wanted him to be alive. The words hurt Stavros very deeply.
After Helena lured and trapped Bobbie, Stefan, Alexis, Luke, Laura, Lucky, Gia, and Nikolas inside the underground lab, Stavros decided to prove his love for his son by showing Nikolas the way out of the maze. While Gia and Nikolas ran to safety, Stavros confronted Luke Spencer. After an altercation, Stavros was left dangling over a bottomless pit. In a final display to thumb his nose at Luke, Stavros threw his hands into the air and fell backwards into the pit.
Though Stavros tumbled into an abyss, it didn't stop him from haunting Nikolas and Gia's dreams.
During the holidays in 2003, Luke had a Christmas Carol-type dream that included Stavros. During the dream, Stavros warned Luke that he was destined for the same fate as Stavros if he didn't change his ways.
In 2013, Luke and Laura's daughter disappeared and they set out to find her. Along the way, they were kidnapped and taken to Cassadine Island. Their captor was revealed to be Stavros. Helena had rescued him from the pit and he had spent years recovering on the island.
Stavros admitted that he had taken Lulu. Laura immediately offered to remain with Stavros on the island permanently in exchange for Lulu's freedom. Stavros explained that he was no longer interested in a future with Laura but instead pursued their past since Lulu reminded him of who Laura had once been. He assured Luke and Laura that Lulu would be remaining with him and that her husband was no longer an issue.
While Stavros bantered with Luke and Laura, Lulu's husband Dante discovered Lulu frozen inside a cryogenic chamber. Luke and Laura assisted Dante in reviving Lulu while Stavros warned them not to touch his "Ice Princess." Luke knocked Stavros unconscious and locked him inside of the frozen room while Laura turned down the temperature and left Stavros to freeze to death.
Unbeknownst to the Spencer family and the rest of Port Charles, Victor Cassadine arranged for Stavros to be revived from his cryogenic stasis. When Stavros regained his strength, he met up with Lulu and Dante and revealed that Lulu would carry his child. He explained that before he had frozen Lulu, he had harvested one of her eggs and created the embryo that would be their child. He injected Lulu with hormones to prepare her body for the implantation. However, Stavros was shot and killed by Dante before Lulu was impregnated. After Stavros' death, Helena took the embryo and vowed that Stavros would live on.