Jason Gideon

Played by Mandy Patinkin, Senior Supervisory Special Agent Jason Gideon was the BAU's best profiler. He helped Derek Morgan and Spencer Reid through their nightmares. He was shown to have a very close relationship with Reid, having hand-picked him from the FBI Academy for his team, helping Reid through many difficulties (including his implied drug use), and even leaving the good-bye letter for Reid to find. Gideon did not know Garcia well, as expressed through an episode wherein he is placed with her while he is on crutches; after they are placed, Garcia complains about him, and he doesn't know her name. Through the first two seasons, Gideon was portrayed to be very good at chess, winning against Reid many times (only exception being Reid's birthday ) and encouraging him to "think outside the box". Prior to the series, he was said to have had a "nervous breakdown" (or "major depressive episode") after he sent six men into a warehouse with a bomb in it; all six agents were killed, and he was heavily criticized about the event. He showed particular dislike for the practice of using religion as a defense or motivation for one's crimes.  At the beginning of Season Three, Gideon abruptly retired from the BAU due to emotional issues brought on by the murder of his girlfriend. His position is now held by his former partner and best friend David Rossi, who has held it to this day. 

Gideon participated in some field operations during his time with the BAU and had the rest of his team "think outside the box" as well, as he made a major advancement by shouting at the top of his lungs with pleas of mercy and, when questioned by his team, he said that the victims were being threatened to be kept quiet as neighbors would have heard the pleas if they were unrestrained. He blamed himself for the torture Reid received from Tobias Hankel as he had ordered Penelope Garcia to add a virus warning to the videos Hankel posted. Gideon also had a son named Stephen. The nature of their relationship has not been directly stated, but it was implied that they have not seen each other very recently. Gideon began to lose confidence in his profiling skills after Frank Breitkopf murdered his girlfriend, Sarah Jacobs. During his final case in Arizona, he further lost faith in his abilities when his decision to release the unsub resulted in the deaths of both the unsub and a young woman. As a result of his actions, Aaron Hotchner was suspended, which was the final straw for Gideon. He then left his cabin shortly afterwards, leaving his gun and badge behind along with a letter for Reid to find as he sought to regain a belief in happy endings.

In the season ten episode "Nelson's Sparrow", Gideon was murdered off-screen, having been shot dead at a close range by a serial killer named Donnie Mallick (Arye Gross), which prompts the BAU team to investigate Gideon's murder. During the flashbacks focusing on a young version of him for the episode which show him working at the BAU in 1978, he is played by Ben Savage.