American pianist, arranger, composer, and bandleader, who composed the jazz and pop standards “Snowfall” and “I Wish I Had You”.
As a youth, he was recognized as an extraordinary talent and formed a travelling duo with Danny Polo, a musical prodigy on the clarinet and trumpet from nearby Clinton, Indiana.
Thornhill entered the Cincinnati Conservatory of Music at the age of 16. That same year he and clarinetist Artie Shaw started their careers at the Golden Pheasant in Cleveland, Ohio, with the Austin Wylie Orchestra. Thornhill and Shaw went to New York together in 1931. Thornhill went to the West Coast in the late 1930s with the Bob Hope Radio Show and arranged for Judy Garland in Babes in Arms. In 1935, he played on sessions with Glenn Miller, including “Solo Hop”, which was released on Columbia Records. He also played with Paul Whiteman, Benny Goodman, Ray Noble, and Billie Holiday. He arranged “Loch Lomond” and “Annie Laurie” for Maxine Sullivan.’
In 1939 he founded the Claude Thornhill Orchestra. Danny Polo was his lead clarinet player. Although the Thornhill band was a sophisticated dance band, it became known for its superior jazz musicians and for Thornhill’s and Gil Evans’s arrangements. The band played without vibrato so that the timbres of the instruments could be better appreciated. Thornhill encouraged the musicians to develop cool-sounding tones. The band was popular with both musicians and the public. Miles Davis’s “Birth of the Cool” nonet was modelled in part on Thornhill’s sound and unconventional instrumentation. The band’s most successful records were “Snowfall”, “A Sunday Kind of Love”, and “Love for Love”.
Thornhill was playing at the Paramount Theater in New York for $10,000 a week in 1942 when he enlisted in the U.S. Navy. As chief musician, he performed shows across the Pacific Theater with Jackie Cooper as his drummer and Dennis Day as his vocalist.
In 1946, he was discharged from the Navy and reunited his ensemble. Danny Polo, Gerry Mulligan, and Barry Galbraith returned with new members, Red Rodney, Lee Konitz, Joe Shulman, and Bill Barber. In the mid 1950s, Thornhill was briefly Tony Bennett’s musical director. He offered his big band library to Gerry Mulligan when Mulligan formed the Concert Jazz Band, but Gerry regretfully declined the gift, since his instrumentation was different. A large portion of his extensive library of music is currently held by Drury University in Springfield, Missouri.
Thornhill died on 1 July 1965 of a heart attack in Caldwell, New Jersey, at the age of 56. In 1984, he was inducted into the Big Band and Jazz Hall of Fame.

Link to Wikipedia biography