The Killers (1946) - Directed by Robert Siodmak and starring Burt Lancaster, one of the greatest classical noirs.
The Killers (!964) - A remake directed by Don Siegel and starring Lee Marvin and Ronald Reagan. I haven't seen it.
Killer's Kiss (1955) - Stanley Kubrick's first feature film, a flashy, low-budget noir shot with an everything and the kitchen sink style that you see in a lot of first films. A lot of fun, the least oppressive of Kubricks.
The Killing (1956) - Kubrick's second film, a terrific heist movie starring Sterling Hayden. Ssome weird middle ground between The Asphalt Jungle and Ocean's 11 (the original).