The Invincible (Polish: Niezwyciężony) is a science fiction novel by Polish writer Stanislaw Lem, published in 1964. The Invincible originally appeared as the title story in Lem's collection Niezwyciężony i inne opowiadania ("The Invincible and Other Stories"). A translation into German was published in 1967; an English translation by Wendayne Ackerman, based on the German one, was published in 1973. An interstellar 2nd-class cruiser called Invincible, lands on Regis III which seems bleakly uninhabited, to investigate the loss of sister ship, Condor.