Thomas Wright "Fats" Waller (May 21, 1904 – December 15, 1943) was an American jazz pianist, organist, composer, and singer. His innovations in the Harlem stride style laid much of the basis for modern jazz piano. His best-known compositions, "Ain't Misbehavin'" and "Honeysuckle Rose", were inducted into the Grammy Hall of Fame in 1984 and 1999. Waller copyrighted over 400 songs, many of them co-written with his closest collaborator, Andy Razaf. Razaf described his partner as "the soul of melody... a man who made the piano sing... both big in body and in mind... known for his generosity... a bubbling bundle of joy". It is likely that he composed many more popular songs than he has been credited with: when in financial difficulties he had a habit of selling songs to other writers and performers who claimed them as their own.

Waller started playing the piano at the age of six and became a professional organist at 15. By the age of 18, he was a recording artist. He was a prolific songwriter, and one of the most popular performers of his era, touring internationally and achieving critical and commercial success in the United States and Europe. He died from pneumonia, aged 39.