A Jolly Bad Fellow (U.S. title: They All Died Laughing; also known as Don Among the Dead Men) is a 1964 British black comedy film directed by Don Chaffey and starring Leo McKern and Janet Munro.

In the film, a university professor advances his career through habitually poisoning his colleagues at the university. It was called "an attempt by Michael Balcon to recapture the magic of Ealing" and gave a rare leading film role to Leo McKern.