In the 1940s and 50s, Trevor played the female lead in several top-quality works, making an especially memorable femme fatale in films noir, particularly as a killer who convinces Burgess Meredith he is wanted for the crime in "Street of Chance" (1942), as the two-faced, wealthy widow in "Murder, My Sweet" (1944) and as a tart-tongued Broadway leading lady in "The Velvet Touch" (1948). But it was perhaps her Oscar-winning performance as Edward G Robinson's humiliated, alcoholic moll in "Key Largo" (1948) that she will be remembered. In one harrowing scene, Robinson taunts her Gaye Dawn to croon the torch song "Moanin' Low" with the promised reward of a much desired drink. After sobbing through a rendition of the tune, Robinson's character cruelly refuses her, claiming her vocal stylings were "rotten".
Trevor continued to alternate between stage and screen, offering fine turns in later films including "Hard, Fast and Beautiful" (1951) and "The High and the Mighty" (1954), for which she earned a third Best Supporting Actress Oscar nomination. She reunited with Robinson, cast as his ranting wife in "Two Weeks in Another Town" (1962) and then segued to more maternal parts as in "The Stripper" (1963) and her final feature, "Kiss Me Goodbye" (1982). Trevor also appeared in a number of TV productions, winning an Emmy as the flighty wife of Fredric March's "Dodsworth" (1956) and made her last appearance in that medium, acting in the 1987 ABC movie "Norman Rockwell's Breaking Home Ties" and appearing as a previous winner at the 1999 telecast of the Academy Awards.