Once a Sinner
- taona: 1950
- Firenena: United Kingdom
- Genre: Drama
- Studio: John Argyle Productions, Butcher's Film Service
- Keyword: british noir, embezzlement, bank clerk
- tale: Lewis Gilbert
- Cast: Pat Kirkwood, Jack Watling, Joy Shelton, Sydney Tafler, Thora Hird, Humphrey Lestocq