Howard Andrew Williams was born in Iowa and started singing professionally with his three older brothers - Bob, Don and Dick - as the Williams Brothers Quartet. They worked in night clubs and on radio and backed Bing Crosby on his number one record Swinging on a Star in 1944.
Embarking on a solo career in the 1950s, he started singing in nightclubs in New York before the burgeoning TV industry provided his next break.
When talk show host Steve Allen launched The Tonight Show in 1954, Williams was an in-house singer - a role he filled for two-and-a-half years, and which led to his first record contract.
Williams became a major star in 1956, the same year that Elvis Presley shot to fame, and was well loved in the 1960s.
He had a number of ballad hits in the 1950s and continued to sell sporadically in the 60s with I Can't Get Used To Losing You (1963), Can't Keep My Eyes Off You (1968) and Happy Heart (1969).
Williams hated his 1957 UK #1 hit, Butterfly so much that he eventually purchased the rights to the track to keep it off the market.
In 1962 he married Claudine Longet, a French actress and singer, with whom he had three children before their divorce in 1975.
Williams continued to play live into his 80s. During a 2007 tour of the UK, he said that performing kept him vital.
In November 2011, he revealed he had been diagnosed with bladder cancer but said he planned to continue performing at his own theatre. He said at the time that bladder cancer was "no longer a death sentence" and that "people with cancer are getting through this thing".
Williams, 84, died at his home in Branson, Missouri on 26 September 2012, a year after being diagnosed with the cancer.