Peter Bishop is a fictional character of the Fox television series Fringe. He is portrayed by Joshua Jackson.

Peter Bishop was born on September 18, 1978, in the alternate universe, to parents Walter Bishop, also known as "Walternate," and his wife Elizabeth Bishop. In 1985, Peter acquired an extremely rare and savage genetic disease. His father, a brilliant scientist (in both universes), worked around-the-clock to save him.

Revealed in the episode "Peter," the Walter Bishop of the prime-universe watched his own son, the prime-universe version of Peter, die because of the same disease. He would frequently watch the other Peter living in the alternate universe via a "trans-dimensional window," which could allow someone to view the Other Side. Eventually, Walter formulated a compound and opened a doorway into the other universe, with the intentions of saving the other Peter from death. However, the vial containing the compound shattered on his way over to the Other Side, so he was forced to kidnap Peter, bring him over to the prime-universe, cure him, and then return him. But, after curing Peter on our side, he and his wife could not find themselves able to return him, so they raised him as their own.

Though at first resistant to this, Peter later grew up oblivious to Walter's deception, apparently forgetting it happened. He repeatedly told Olivia Dunham that he was never fond of his father, and even recalled times when Walter experimented on him. It is implied that Walter did this to see how Peter's body reacted to moving between universes. In 1991, Walter's lab assistant, Dr. Carla Warren, was killed in a fire in his lab, and Walter was locked away inside St. Claire's Mental Institution. Peter later admits to have never visited Walter, and continued to grow up despising his father. His hatred towards Walter grew to the point that Peter took books belonging to Robert Bishop, Walter's father, and sold them for money, an action that affected Walter greatly when he discovered this in 2009.

Even with his genius I.Q. level of 190, and fluency in English, Arabic, Persian, Latin, Greek, Cantonese, Russian, and Spanish, Peter became a college drop-out with gambling debts, a jack-of-all-trades, and a master con artist. He falsified a chemistry degree from MIT and managed to publish a few papers before his con was discovered. The only time he spoke to his father during Walter's initial 17-year stay inside St. Claire's was when Walter phoned to tell him that Elizabeth had died in a car crash, though Peter later discovered that she actually committed suicide because of the guilt she carried from keeping him in this universe ("The Man From The Other Side.") Additionally, Peter has trouble with the mafia because he owes an undisclosed amount of money to "Big Eddie," a crime lord who had been hunting him for some time.

Peter was first seen setting up a business deal in Baghdad, Iraq, when he was blackmailed by Olivia Dunham to gain access to his father. Peter releases Walter from St. Claire's so he can develop a cure for Olivia's lover, John Scott, though John is discovered to be a traitor (it is revealed in episode 1x13, "The Transformation," that John was actually an undercover agent working with the National Security Agency, and his love for Olivia was real).

For the majority of the early episodes, Peter despises working with his father, and in episode 1x04, "The Arrival," he prepares to leave Boston for good. But, he comes in contact with The Observer known as "September," who appears to read Peter's mind. Following this incident, Peter realizes that "The Pattern" does actually exist, and vows to remain in Boston until he discovers the truth, becoming a civilian consultant for U.S. Department of Homeland Security, in the area of fringe science.

By the culmination of season one, Peter and Walter appear to have completely reconciled. Peter even builds his father a device that could repair his water-damaged records, in episode 1x19, "The Road Not Taken." By the first season finale, "There's More Than One of Everything," Walter reveals to Peter the existence of the alternate universe, without telling him that is where he was born. Peter plays a key role in stopping David Robert Jones from opening a door to the Other Side, to kill William Bell, by closing the hole shut while Jones' body is only halfway through, slicing him in half. By this time, Walter begins leaving Peter notes explaining where he has run off to, making Peter remark to Astrid Farnsworth, "our little boy has grown up," solidifying his newfound love for his father.