Billy Lyall (26 March 1953 – 1 December 1989) was a Scottish musician.
Born William Lyall in Edinburgh, Scotland, Lyall was a keyboard player, vocalist and occasional flautist with Pilot, and an early member of the Bay City Rollers. He also contributed to The Alan Parsons Project with fellow Pilot members, and released a solo album, Solo Casting in 1976. Lyall died of AIDS-related causes in 1989, aged 36. Tam Paton later revealed that Lyall was gay.