Following a series of conventional Westerns and films noirs, as well as the Marilyn Monroe vehicle River of No Return (1954), Mitchum appeared in Charles Laughton's only film as director: The Night of the Hunter (1955). Based on a novel by Davis Grubb, the thriller starred Mitchum as a monstrous criminal posing as a preacher to find money hidden by his cellmate in the cellmate's home. His performance as Reverend Harry Powell is considered by many to be one of the best of his career. Stanley Kramer's melodrama Not as a Stranger, also released in 1955, was a box-office hit. The film starred Mitchum against type, as an idealistic young doctor, who marries an older nurse (Olivia de Havilland), only to question his morality many years later. However, the film was not well received, with most critics pointing out that Mitchum, Frank Sinatra, and Lee Marvin were all too old for their characters. Olivia de Havilland received top billing over Mitchum and Sinatra.
On March 8, 1955, Mitchum formed DRM (Dorothy and Robert Mitchum) Productions to produce five films for United Artists; four films were produced. The first film was Bandido (1956). Following a succession of average Westerns and the poorly received Foreign Intrigue (1956), Mitchum starred in the first of three films with Deborah Kerr. The John Huston war drama Heaven Knows, Mr. Allison, starred Mitchum as a Marine corporal shipwrecked on a Pacific Island with a nun, Sister Angela (Deborah Kerr), as his sole companion. In this character study, they struggle to resist the elements and the invading Japanese army. The film was nominated for two Academy Awards, including Best Actress and Best Adapted Screenplay. For his role, Mitchum was nominated for a BAFTA Award for Best Foreign Actor. In the WWII submarine classic The Enemy Below (1956), Mitchum gave a strong performance as U.S. Naval Lieutenant Commander Murrell, the captain of a U.S. Navy destroyer who matches wits with a German U-boat captain Curt Jurgens, who starred with Mitchum again in the legendary 1962 movie The Longest Day. The film won an Oscar for Special Effects.