A clarinetist, saxophonist, and big band leader, he had a marvelous penchant for bringing together all-star ensembles, known as "herds." Who is he?

Woodrow Charles Herman, also known as Woody Herman.

Explanation:

Woodrow Charles Herman was an American jazz clarinetist, alto and soprano saxophonist, a band leader and also a singer. He used to lead various groups called "The Herd" and gained prominence in the late 1930's until his death in 1987. "The Herd" became synonymous with him, with the orchestra famous worldwide. He had a penchant for bringing together all-star ensembles in his orchestra, largely known as "The Herd".