There has been speculation whether Brad Pitt appeared on Little House on the Prairie or not. And the speculation seems to have begun with a radio station trivia question that implied Brad Pitt did appear on the show at some point.
Brad Pitt did not appear in any Little House on the Prairie episodes, nor does it seem that he appeared as an uncredited extra on the show either during the show’s long-running duration.
Brad Pitt did appear in several western-style movies, which could also be why some might misremember him as having appeared on Little House on the Prairie at some point. He appeared in The Assassination of Jesse James as Jesse James himself, as well as Legends of the Fall, both set in frontier / pioneer settings.