Frank Booth - Blue Velvet (1986)
With such a long and varied career, it's near-impossible to select just one role that defined Dennis Hopper. Though the image of maniacal, sadistic Frank Booth chugging on his gas tank while unleashing a tirade of profanities while doing horrible, horrible things to Isabella Rosselini's Dorothy, stands out as one his most iconic and crude. It was the role that revived Hopper's career after years spent in a drug-induced hell that saw him stage a suicide attempt/daredevil act in the name of 'art'. The most unnerving, expletive-laden performance of all time? It's a close contender.