Andy Williams, the iconic singer of the Academy Award-winning song "Moon River," has died at age 84.

The cause was complications from bladder cancer, according to his publicist, Paul Shefrin. Williams announced he had cancer last year, and until recently was thought to be in good health.

From 1962 to 1971, Williams hosted "The Andy Williams Show" on NBC, a variety hour featuring singers and entertainers. He owned the Moon River Theatre in Branson, Mo., named after the song that made him famous.

"Moon River" was written by Johnny Mercer and composed by Henry Mancini for the 1961 film "Breakfast at Tiffany's." In the film, it was sung by Audrey Hepburn, but Williams recorded it later that year and sang it at the 1962 Academy Awards.

The song became his theme, and he used it during the introduction to his television show.

Even after he stopped recording, Williams' famous songs were used in modern movies. "The Most Wonderful Time of the Year" appeared in 2003's "Bad Santa," and "Bridget Jones's Diary" used "Can't Take My Eyes Off You" in 2001.

Williams was born in Wall Lake, Iowa, in 1927. He sang with his three older brothers in a church choir, eventually forming The Williams Brothers Quartet.

He went solo in 1953, appearing on "Tonight Starring Steve Allen," the precursor to "The Tonight Show." Williams signed with Columbia Records in 1961.

Though he was a lifelong Republican, Williams was good friends with Robert F. Kennedy, the younger brother of U.S. President John F. Kennedy. He was present at the Ambassador Hotel in Los Angeles when the younger Kennedy was assassinated by Sirhan Sirhan in 1968, and Williams sang at his funeral.

Williams and his wife named their son Bobby after their slain friend, and Wiliams raised funds for the 1972 presidential campaign of Democratic candidate George McGovern.

However, Williams recently caused a stir when in 2009, according to the Daily Telegraph, he accused President Barack Obama of "following Marxist theory" and "wanting the country to fail."

He gave right-wing radio host Rush Limbaugh permission to use one of his songs on air, though the license was later revoked by Williams' recording company.