Farfour is an infamous animatronic in DSAF. He is based on a character in Tomorrow's Pioneers.
He plays a major role in the first game, where he is referenced on the tour, with Phone Guy saying "We used to have a bear and rat suit." He is then seen in the Mediocre ending, where he kills old sport. He is also seen in the Soapy Ending, if you choose only the Rat, and in the Gnarly Ending, if you choose him along with Breadbear. He also appears in The End and the Awesome Ending, where he tries to destroy Freddy's but is stopped by the Real Fredbear.
He isn't shown in the second game, but has minor appearances as a toy in the prize corner, and a costume that the human version of Phone Guy wears before being killed by Henry.