William Jayne Jacoby (born April 10, 1969), known professionally as Billy Jayne and previously Billy Jacoby is an American actor, known for his roles in the teen comedy film Just One of the Guys (1985) and in the teen sitcom Parker Lewis Can't Lose (1990–1993). His siblings, Robert Jayne, Susan Jayne, Laura Jacoby, as well as his half-brother Scott Jacoby are also actors.^[1]

Jayne was born in Flushing, Queens, New York City, on April 10, 1969. He is of Jewish descent.^[2] At the age of three, he was visiting his older half-brother Scott Jacoby on the set of That Certain Summer, for which Scott won an Emmy for Best Supporting Actor.^[3] The director needed someone to play Jacoby in flashbacks, and Jayne was selected and began his career.

Although Jayne's birth name was not Jacoby, when he started his career his mother thought it would be best if he used Jacoby, the last name of his already established half-brother. At the age of 17, however, Billy Jacoby changed his professional name to Billy Jayne to coincide with his birth name.

Jayne was a child actor from the mid to late 1980s, starring in numerous guest appearances on TV shows such as Trapper John, M.D., The Golden Girls as Blanche's 14-year-old rebellious grandson David, The A-Team, and 21 Jump Street. He is also known for the role of Buddy, the brother of Terri, in Just One of the Guys from 1985.

From 1990 to 1993, Jayne starred in the teen sitcom Parker Lewis Can't Lose alongside actor Corin Nemec. After the series ended, he had smaller roles in shows such as Renegade, Murder One (1995), Walker, Texas Ranger (1996), Charmed (1999) and Cold Case (2009).