Mr. Kiley, 76, had struggled with bone marrow disease and was too ill to attend his Theatre Hall of Fame honor earlier this year at the Gershwin Theatre in New York City.
E! Online reported that Mr. Kiley's death was confirmed March 5 by a funeral director in Warwick, NY, but no other details were immediately available.
In addition to creating and nabbing a Best Actor Tony for the dual roles of Cervantes and Don Quixote in the smash 1965 musical, Man of La Mancha, Mr. Kiley won a Best Actor Tony Award for 1959's Redhead with Gwen Verdon and sang "The Sweetest Sounds" opposite Diahann Carroll in the groundbreaking 1962 musical, No Strings, with music and lyrics by Richard Rodgers. He appeared in Kismet in 1953, playing the Caliph and introducing another major musical theatre hit: "Stranger in Paradise," based on a theme by Borodin.
His sonorous voice was heard on radio serials, commercials and voiceovers (the voice of the "Jurassic Park" tram in the Spielberg film) and his late-career TV work included roles in "Ally McBeal," "Picket Fences," "Star Trek: Deep Space Nine" and the miniseries, "A Year in the Life," which later became a regular series on NBC.
Born in Chicago in 1922, he attended Loyola University and Barnum Dramatic School in Chicago, 1941-42. He served as a gunnery instructor in the U.S. Navy and came to New York City in 1947. He would have turned 77 March 31.
Mr. Kiley was known for his virile, commanding presence and his versatility, moving easily between classical roles (Misalliance on Broadway), musicals (1964's I Had a Ball, 1968's Her First Roman) and contemporary plays (understudying Anthony Quinn and later taking over for him as Stanley in a tour of A Streetcar Named Desire).
His films include "The Blackboard Jungle," "The Little Prince," "Looking for Mr. Goodbar" and "Patch Adams."
He is survived by wife Patricia and six children.
