Once a Jolly Swagman is a 1949 British film starring Dirk Bogarde, Bonar Colleano, Bill Owen, Thora Hird and Sid James. It is centred on the sport of motorcycle speedway racing, which was at its peak of popularity at the time. It was released in the U.S. as Maniacs on Wheels.

The film is based on the 1946 novel by Montagu Slater.The title of the film refers to the first line of the Australian song "Waltzing Matilda".

Director Jack Lee later said he enjoyed making the film "because it was physical, there was action and I had good actors."