"Deja Q" is the 13th episode of the third season of the American science fiction television series Star Trek: The Next Generation, and the 61st episode of the series overall. This episode aired on syndicated television in February 1990. In this episode, as the 24th-century crew of the starship Enterprise D struggles to prevent a moon from falling out of orbit, their situation is further complicated by a visit from a powerful nemesis named "Q" (John de Lancie), who informs them that he has been stripped of all his powers and must live out a mortal life.