Taxi Driver

The main character -- lonely, depressed, and alienated -- starts to slide into a deteriorating mental and emotional state in which he has delusions of grandeur as well as homicidal and suicidal thoughts. The end of the movie is an ironical twist on the consequences of his actions, and despite what society now thinks of him, he shows no real clear signs that he will change. 

Climactic scene is a blood-drenched apartment gun battle -- characters shot in the chest, hand, arm. Suicide by a gun to the head prevented only because the gun no longer has any bullets. Lead character shoots and kills a would-be robber of a liquor store; the clerk then starts to beat the dead body of the assailant with a wooden club. Lead character buys a collection of guns from an illegal arms salesman; when the lead character sees how a gun feels in his hand, he aims it out the window as the camera shows his point of view and the gun pointed at two pedestrians talking on the sidewalk a few stories below.  Assassination of a politician narrowly averted. 

Constant profanity. "F--k" and "N" word. Various racial and homophobic slurs. "C--ts," "p---y," "c--k," "bitch," "ass," "hell." Bickle mentions having to clean off semen (he uses a slang term) from the backseat of his taxi at the end of every shift. A pimp tells the lead character of the sexual acts he can perform on a 12-year-old prostitute for the money he spends. A cabbie regales fellow cabbies in an all-night cafeteria with over-the-top tales of his sexual experiences. 

Lead character often shown taking pills presumed to be amphetamines. He often keeps a bagged bottle of booze in his pocket and takes sips while walking down the street. Beer drinking. Smoking.