Withnail and I is a 1987 British black comedy film written and directed by Bruce Robinson. Loosely based on Robinson's life in London in the late 1960s, the plot follows two unemployed actors, Withnail and "I" (portrayed by Richard E. Grant and Paul McGann, respectively) who share a flat in Camden Town in 1969. Needing a holiday, they obtain the key to a country cottage in the Lake District belonging to Withnail's eccentric uncle Monty and drive there. The weekend holiday proves less recuperative than they expected.

Withnail and I was Grant's film debut and established his profile. Featuring performances by Richard Griffiths as Withnail's Uncle Monty and Ralph Brown as Danny the drug dealer, the film has tragic and comic elements and is notable for its period music and many quotable lines. It has been described as "one of Britain's biggest cult films".

The character "I" is named "Marwood" in the published screenplay but goes unnamed in the film credits.