Whitmore died at his home in the seaside enclave of Malibu, just northwest of Los Angeles, of lung cancer, with which he was diagnosed in November, according to his son, Steve.

A New York native, Whitmore served in the Marine Corps during World War II and began appearing in stage productions in New Hampshire in the late 1940s.

The bushy-eyebrowed actor made his Broadway debut in "Command Decision" in 1947, and earned a Tony Award for best performance by a newcomer.

Whitmore picked up an Oscar nomination for a supporting role in his first major movie, the 1949 combat drama "Battleground," and an Academy Award nomination as best lead actor for his 1975 portrait of Truman in "Give 'em Hell Harry!"

He originated the Truman role in the stage version of that production, one of three solo vehicles during the 1970s that earned him the moniker "King of the One Man Show." The two others were the title role in "Will Rogers' USA" and as "Theodore Roosevelt in "Bully."

Whitmore also had a prolific career as a character actor on television, appearing in such series as "The Twilight Zone," "Rawhide," "Dr. Kildare" and "The Detectives."

But he was better known to a younger generation of TV viewers as the longtime commercial spokesman for the plant food brand Miracle-Gro. He also earned an Emmy Award as a guest actor in a drama series for an episode of "The Practice."

Among his more notable movie credits were the original "Planet of the Apes," as head of the simian assembly, and "The Shawshank Redemption," playing an inmate who commits suicide.

Other film credits include "The Asphalt Jungle," "Kiss Me Kate," "Oklahoma!" and "Madigan."