Howard Green Duff (November 24, 1913 – July 8, 1990) was an American actor of film, television, stage, and radio

Duff was born in Charleston, Washington, now a part of Bremerton. His first film role was as an inmate in Brute Force. His other early movies include The Naked City (1948), All My Sons (1948), Panic in the City (1968), In Search of America (1971), A Wedding (1978) and No Way Out (1987). Duff, (according to her biographer, Lee Server, had a tempestuous relationship with Ava Gardner in the late 1940s), appeared in a number of films with his first wife, actress/director Ida Lupino, a partner with Dick Powell in Four Star Television. They married in 1951, separated in 1966 and divorced in 1984. They had a daughter, Bridget (born April 23, 1952).

One of Duff's best later performances was as Dustin Hoffman's attorney in the Academy Award-winning Kramer vs. Kramer (1979). In the 1980s, he was a familiar face on television appearing on dramas such as NBC's Flamingo Road and Knots Landing, and Dallas, both on CBS.

Duff played Dashiell Hammett's private eye Sam Spade on radio from 1946-1950, starring in The Adventures of Sam Spade on three different networks - ABC, CBS and NBC. In 1951 Steve Dunne took over the role of Sam Spade. From January 1957 through September 1958, Duff appeared with Lupino in the CBS comedy Mr. Adams and Eve in which they played husband and wife film stars named Howard Adams and Eve Drake. From October 1960 through April 1961, Duff played Willie Dante, owner of the nightclub Dante's Inferno, in the NBC mystery adventure series Dante, and from September 1966 through January 1969, he portrayed Detective Sergeant Sam Stone in the ABC police drama Felony Squad with costar Dennis Cole.

Duff died at age 76 of a heart attack, on July 8, 1990 in Santa Barbara, California. He was survived by his daughter, actress Bridget Duff and his second wife, Judy Jenkinson.

Played Dashiell Hammett's famous character in "The Adventures of Sam Spade" on radio.

Father of Bridget Duff.

He played the detective, "Sam Spade" on TV, and before that on radio.

He was scheduled to star in a 1958 detective/mystery series called "The Green Peacock" following the cancellation of his sitcom "Mr. and Mrs. Eve," but even though episodes were produced, they were never broadcast. Episodes were written by writers such as Daniel Mainwaring and William Spier. Ramon Navarro was the co-star.