The unnamed passenger is a minor but important character in the 1976 film, Taxi Driver.
He was portrayed by Martin Scorsese, who also directed the movie.
He is a man whom the protagonist, Travis Bickle, picks up in his cab. The man tells Travis to pull over to the curb and keep the meter running. He directs Travis' view to a second-story apartment window, in which the silhouette of a woman can be seen. The man informs Travis that the woman is his wife, but that the apartment is not his. He states that a "nigger" lives there, and tells Travis that he intends to kill his wife with a .44 Magnum. He describes his plans to Travis in gruesome and suggestive detail, and then is not seen again for the rest of the movie. Whether he actually carries out his plan is not stated, but his appearance sparks a change in the course of the movie. He plants the idea of extreme violence into Travis' head, and Travis purchases a .44 Magnum because the man had mentioned it. A common theory is that the unnamed passenger does not even exist, and is a manifestation of the anger and hatred that Travis feels for the world.