William "Billy" Gussak (c. 1920 – 1994) was an American jazz and recording session drummer, best known for being the drummer on the classic 12 April 1954 recording of "Rock Around The Clock" by Bill Haley and His Comets. Some sources incorrectly spell his name as Guesak.

Gussak was a well-respected session drummer, who had been used by Haley on some of his 1953 recordings, including "Real Rock Drive" and "Crazy Man, Crazy" in preference to the Comets' usual live drummer Dick Boccelli (also known as Dick Richards). According to one source , it was record producer Milt Gabler who insisted on using Gussak. "Gabler, who wanted to stress the big beat sound that he could get from [recording studio] Pythian Temple's acoustics, brought in his own session drummer ... Beginning with his three rim shots at the start of the record, Gussak would drop echoed snare bombs throughout, giving a dynamic to "Rock Around The Clock" that Haley's material had never had before."

Gussak continued as a studio drummer after "Rock Around The Clock" became successful, recording occasionally with Haley through 1954/55 and then recording with The Jodimars, the members of the Comets who had split away from Haley. Gussak later moved to California, where he recorded with Perry Como among others, before retiring due to arthritis. In the early 1960s he collaborated on some songs with eccentric musician Stephen "Brute Force" Friedland, at the time the boyfriend of his daughter.

Gussak is also credited with a number of patents in relation to drum design. He died in 1994.