The fourth season of the American science fiction television series Fringe premiered on Fox on September 23, 2011, and concluded on May 11, 2012, consisting of 22 episodes. The series is produced by Bad Robot Productions in association with Warner Bros. Television, and its showrunners were Jeff Pinkner and J.H. Wyman. The show was officially renewed for a fourth season on March 24, 2011. Lead actors Anna Torv, John Noble, and Joshua Jackson reprised their roles as FBI agent Olivia Dunham and the father-son duo Walter and Peter Bishop. Previous series regulars Lance Reddick, Jasika Nicole, and Blair Brown also returned. Previous recurring guest star Seth Gabel was promoted to series regular. Prominent guest star Leonard Nimoy and first season guest star Jared Harris reprised their roles in