In the late 1940s, Marshall was the girlfriend of director Howard Hawks; she had a small but significant role in his I Was a Male War Bride (1949).

She married three times, her first husband being the cameraman Allen Davey.

Her second husband (from 1952 until 1959) was Stanley Donen with whom she had two sons Peter (born 20 December 1953) and Joshua (born 10 August 1955).

In 1963 she married the actor Robert Wagner, with whom she had one child (the television presenter Katie Wagner) before they divorced in 1970.[citation needed]