Anthony John Medeski (b. 28 June 1965) is an American jazz keyboards player and composer.Medeski was born in Louisville, Kentucky, and grew up in Florida. After piano lessons (starting when he was five years old), he began as a teenager to perform with musicians such as Mark Murphy and Jaco Pastorius.

In 1983 began studying piano at the New England Conservatory in Boston, where he also performed as a sideman with Dewey redman, Billy Higgins, Bob Mintzer, Alan Dawson, and Mr. Jellybelly.Highly technically gifted, but also soulful, Medeski seems equally at home performing in accessible groove based funk/jazz (some MMW albums and A gogo with John Scofield) as he is in the more experimental side of things; such as John Zorn's Electric Masada or his collaboration with David Fiuczynski, Lunar Crush.

He regularly uses multiple effects including but not limited to electronic synthesizers to create unique sounds.Medeski is best known for his work with Medeski, Martin and Wood, often known as MMW, with drummer/percussionist Billy Martin and bassist Chris Wood.

He also performs in a band called The Word, made up of Robert Randolph (pedal steel) from Robert Randolph and the Family Band, brothers Luther Dickinson (guitar) and Cody Dickinson (drums), and Chris Chew (bass) of North Mississippi Allstars.

On July 14, 2006, John Medeski & The Itch performed their debut gig at the All Good Music Festival in Masontown, WV. "The Itch" consists of Eric Krasno (guitar) of Soulive and Adam Deitch (drums) with Medeski playing left-hand keyboard bass.