Corpse is one of the mercenaries in Black's group. He only appears in S.T.A.L.K.E.R.: Call of Pripyat.
He doesn't have any background information, nor he is much of importance to the story.
If the player takes the administrative documents at the Jupiter plant, Corpse and the rest of the Black's group will attack the player. That's the only place he will appear in the entire game.