The Driller Killer (1979)

Reno is an artist struggling to survive in NYC. He draws inspiration from scenes of daily street life and occasional random violence. Under pressure to finish his oft-delayed grand masterpiece, his psychotic alter-ego takes over and he begins killing random vagrants to boost his creativity, not quite realizing that it is happening in reality. When an art dealer grimly rejects Reno's finished masterpiece, Reno's mental condition quickly deteriorates.