Jack Shephard Played by: Matthew Fox
Reason for the Flight: Bringing his father's body back to the U.S.
Profession: Spinal surgeon at St. Sebastian Hospital in Los Angeles
Pre-Crash: Jack miraculously saved a woman with a spinal injury, Sarah, and then married her. She later left him for another man. At one point, Jack suspected that Sarah was seeing his overbearing father, who, like Jack, was a spinal surgeon at St. Sebastian hospital.
Jack accused his alcoholic father, Christian Shephard, of sleeping with his wife, and also turned him in to the medical board for operating while under the influence.
Jack went to Phuket, where he met Achara, and Christian went on a drinking binge in Australia, and that is believed to be the cause of his death. Jack went to Australia to search for him at his mother's insistence, and was returning to the states with his father's body when the plane went down.
Island: Being a doctor, most of the survivors looked to Jack as their leader, but Jack didn't want to be their leader. He finally came around, but often had conflict with the other strong personalities on the island.
Jack was attracted to Kate and in competition with Sawyer for her affections. He also seemed to be developing a relationship with Ana-Lucia before her death.
Jack was captured by the Others and forced to live in a small room. He formed a relationship with Juliet who persuaded him to remove a tumor from Ben's spine.
Juliet was shunned by the Others after shooting fellow Other, Danny Pickett, and went with Jack to live on the beach with the Flight 815 survivors.
A woman parachuted onto the island, followed by her team of an additional four people who at first claimed to be there to rescue them, but it was later discovered they were not. Jack became friends with the helicopter pilot and was flown off of the island with Kate, Sun, Aaron, Hurley, and Sayid.
Post-Island: Jack meets Carole Littleton at his father's funeral and learns that Claire is his half sister.
Shortly after Kate's trial, Jack moves in with her and Aaron and is very happy, but starts to go downhill when he thinks he sees his father. From then on, Jack seems to always be under the influence of drugs or alcohol. He almost commits suicide, but stops in order to help a mother and son who had just been in a vehicle accident.
Jack desperately wants to get back to the island, and begs Kate to meet him. He tells her that they should be on the island, but she doesn't agree.
Jack goes to a funeral home, where he sees Locke in a casket. Ben says that in order to get back to the island, they all have to go, including Locke.
Back on the Island: Once they get back on the island, Jack is convinced that they have to carry out Daniel Faraday's plan and drop the bomb at the Swan construction site. They do, but nothing happens. Juliet gets sucked into the hole and they pass out, waking up in 2007, but still on the island.
Jacob nudges Jack in the right direction through Hurley, and Jack takes leadership of the island. Desmond had removed a cork at the heart of the island that allowed Jack and Kate to kill Man in Black who had been masquerading as John Locke. In order to save his friends, Jack goes into the light cave at the heart of the island and returns the cork, then he walks through the bamboo forest and falls to the ground. He dies, with Walt's dog, Vincent, by his side, in the same spot he'd landed after the original plane crash.
Flash-Sideways: Jack is divorced and has a teenage son that he only sees about once a month. He is trying really hard to have good communication with his son, David. Over time, his relationship with David improves and we see that Juliet is his ex-wife. Jack begins seeing flashes of his life on the island, but doesn't quite remember and doesn't know that the island events really happened. When Jack finally remembers everything, he goes to a church where all the Losties are, even the ones who had died. Christian tells Jack that they made this place so that they could all move on together to whatever is next.
Strong Relationships: While once rocky, his relationship with Sayid became solid. He and Sun often work together to help the ill and wounded. He also had a strong relationship with Ana-Lucia and has developed a strong relationship with Juliet.
Rocky Relationships: Kate (he loves her so much he sometimes hates her), Sawyer (they are in competition for the same woman, but also disagree on how to survive on the island, yet sometimes they work well together), and especially Locke (Jack and Locke have always struggled for power, and Jack believes in science, while Locke believes in faith). The hardest relationship Jack has is the one with his father. Jack never felt he could live up to his father's expectations.
- Episode 1x5, White Rabbit.
- Episode 1x11, All the Best Cowboys Have Daddy Issues.
- Episode 1x20, Do No Harm.
- Episode 1x23, Exodus Part 1.
- Episode 2x1, Man of Science, Man of Faith.
- Episode 2x11, The Hunting Party.
- Episode 3x1, A Tale of Two Cities.
- Episode 3x9, Stranger in a Strange Land.
Sawyer: Sawyer meets Jack's father in an Australian bar. (Ep: 1x16, Outlaws).
- Hurley: Hurley's lottery official (Ep: 1x18, Numbers and Ep: 2x4, Everybody Hates Hugo) is the anesthesiologist in one of Jack's surgeries (Ep: 1x11, All the Best Cowboys Have Daddy Issues).
Shannon: Sarah met Jack as he worked on her in the hospital after he decided to work on her instead of a man who was also involved in the accident. The man, Shannon's father, died, and Jack ended up marrying Sarah. (Ep: 2x1, Man of Science, Man of Faith).
Desmond: Jack and Desmond run in the same stadium and have a conversation. (Ep: 2x23, Live Together, Die Alone).
- Ana-Lucia and Jack meet each other in the airport bar before boarding Flight 815 (Ep: 1x23, Exodus Part 1).
- Ana-Lucia pulls a gun on Travis during a domestic disturbance (Ep: 2x8, Collision). This is the same man who threatens to sue St. Sebastian after Jack's father operates on his wife and she dies (Ep: 1x11, All the Best Cowboys Have Daddy Issues).
Ana-Lucia meets Jack's father, Dr. Christian Shephard, in the bar of the airport where she works. She goes to Sydney with him, but decides to return home, which puts her on Flight 815 (Ep: 2x20, Two for the Road)
- Claire: In one of Claire's flashbacks (Ep: 3x12, Par Avion) we find out that as a teen Claire met her biological father, Christian Shephard, who is also Jack's father. Claire didn't know his name and so Claire and Jack have no idea that they have the same father.