Thomas Francis "Tommy" Dorsey, Jr. was an American jazz trombonist, trumpeter, composer, and bandleader of the Big Band era. He was known as "The Sentimental Gentleman of Swing", because of his smooth-toned trombone playing. Although he was not known for being a notable soloist, his technical skill on the trombone gave him renown amongst other musicians. He was the younger brother of bandleader Jimmy Dorsey. After Dorsey broke with his brother in the mid-1930s, he led an extremely popular and highly successful band from the late 1930s into the 1950s.