Jeff Duncan (born January 28, 1966) is an American heavy metal musician, best known for being the rhythm guitarist of Armored Saint[1] and previously Odin.

In 1989, Duncan joined Armored Saint and made his recording debut on 1991's Symbol of Salvation, co-writing several songs, including the MTV video/single, "Last Train Home."

He is currently playing shows with Armored Saint, DC4, and the Las-Vegas based band, The Bones, featuring Sean Koos (ex-Joan Jett & The Blackhearts), Patrick Vitagliano (ex-John Connelly's Nuclear Theory), and brother Shawn Duncan.

At one point he was also in a band called The Thornbirds, which also included Russ Parrish and Darren Leader from Steel Panther as well as bass player Dean Cameron.

Duncan and Odin would reunite for the first time in 2003 and have performed live as recently as 2018 in conjunction with the re-release of Don't Take No for an Answer and Fight For Your Life on Dave Ellefson's EMP label.