David Rossi

Played by Joe Mantegna, Senior Supervisory Special Agent David Rossi, a "'founding father' of the BAU", was in early retirement from 1997 until his voluntary return to the BAU in 2007, replacing Jason Gideon, who had abruptly resigned from the BAU. He had retired in order to write books and go on lecture tours, but he returned to settle some unfinished business that was not immediately specified. It was later revealed that the case involved three young children whose parents had been murdered in a possible home-invasion case that had remained unsolved. This case haunted Rossi for twenty years and prompted him to return to the BAU, where he eventually solved it.David Stephen Rossi is a fictional character in the CBS crime drama Criminal Minds, portrayed by Joe Mantegna. He is a Supervisory Special Agent of the FBI's Behavioral Analysis Unit, and has appeared from the episode "About Face", which was originally broadcast on October 31, 2007, during the show's third season. He is also portrayed as a younger man by Robert Dunne, in flashbacks as a Marine infantry private in Vietnam in 1969 and in his earlier years with the BAU in 1978.

Rossi begins the series returning to the FBI after a lengthy period of being semi-retired, with his return due to "unfinished business". He is shown to be emotionally tied to Aaron Hotchner, as they both worked together during the early days of the Behaviorial Analysis Unit. Rossi is also a writer, and is one of the team's senior and most decorated profilers. 

He replaced Jason Gideon, who was written out following Mandy Patinkin's abrupt departure from the series.

 Mantegna has stated in an interview that the character was named after one of the policemen who had testified at the O. J. Simpson trial. Rossi's middle name, Stephen, was revealed in a flashback near the end of the tenth season episode, "Nelson's Sparrow." After Rossi has deduced that Jason Gideon is about to become a father, Gideon asks Rossi what his middle name is. This is followed by a present-time scene where Rossi greets Gideon's son, Stephen, by name. (The "ph" spelling of the name was used in the episode's end credits.