LOS ANGELES -- The actor who first immortalized real-life crimefighter Eliot Ness on the small screen has died.

Robert Stack, who starred in "The Untouchables" and later on "Unsolved Mysteries," died Wednesday at his home. He was 84.

His wife says Stack died of heart failure. He had been treated for prostate cancer in October.

Stack won an Emmy for playing Ness in television's "The Untouchables" from 1959 to 1963. Stack reprised the role of the FBI agent in the 1991 television movie "The Return of Eliot Ness."

He had been the host of the popular television series "Unsolved Mysteries" since 1987. He was nominated for an Emmy for his hosting duties in 1995.

Stack was born Robert Langford Modini on Jan. 13, 1919, in Los Angeles. His big screen debut came in the 1939 comedy-drama "First Love," where he starred opposite Deana Durbin. He had roles in several more movies until he took the role of Ness for television in 1957.

Stack was nominated for an Oscar for "Written on the Wind" in 1957, an award he once said he felt he should have won.

While Stack was best known for his dramatic work, he also enjoyed doing comedies. He was in the 1980 hit "Airplane," as well as "Caddyshack II," "1941," "Joe Versus the Volcano" and "Beavis and Butt-head Do America," as the voice of Agent Flemming.

Among Stack's last credits include voice roles for the television shows "Hercules," "Butt Ugly Martians" and the movie "Recess: School's Out."