Williams, born Howard Andrew Williams in Iowa, first started singing with his brothers in the late '30s. Together the quartet joined entertainer Kay Thompson in her nightclub act. After breaking up in 1952, Williams launched his solo career where he eventually landed a spot on The Tonight Show and a Columbia Records contract. His rendition of the Breakfast at Tiffany's theme "Moon River" became his signature hit.
Last year, Williams announced at his Branson, Mo., Moon River Theatre that he was being treated for bladder cancer. "This is no longer a death sentence," he told concertgoers. "People with cancer are getting through this thing. They're kicking it, and they're winning more and more every year. And I'm going to be one of them."
Williams is survived by his second wife Debbie Williams and his three children from his first marriage to Claudine Longet.