Leo David William Lyons (born 30 November 1943) is an English musician, who was most known as the bassist of the blues rock band Ten Years After.

In 1962, along with band-mate Alvin Lee, his band The Jaybirds performed at The Star Club in Hamburg, Germany.

The band established residency at London's famous Marquee Club, and published a debut album on Deram Records.

After Fillmore West founder Bill Graham heard a copy of the band's first album, he immediately sent a letter offering to book Ten Years After on an extended tour in the United States.

As a producer, Lyons worked with a broad variety of musicians, including UFO, Waysted, Motörhead, Richard and Linda Thompson, and many others.