David Lee Marks (born August 22, 1948) is an American guitarist, singer and songwriter. He is best known as a member of the rock band The Beach Boys, with whom he recorded five studio albums, and of whom he was a performing member from 1962 until the late fall of 1963 (and a legal member until September 27, 1967), performing again from 1997 until 1999, and lastly in 2012. Following his initial departure from the band, Marks fronted The Marksmen and performed and recorded as a session musician. To date, he has released three solo albums, Work Tapes (1992), Something Funny Goin' On (2003) and I Think About You Often (2006).

A neighbor of the Wilson family – including The Beach Boys' founding members Brian, Dennis, and Carl Wilson – and a frequent participant at the Wilson family's Sunday night singalongs, thirteen-year-old Marks officially joined The Beach Boys in February 1962 as its rhythm guitarist, replacing founding member Al Jardine during his brief pursuit of a career in the air industry. Over the next year, overlapping for some time with the returned Jardine in a six-member lineup (including founding member and Wilson cousin Mike Love), Marks was a band member on its first four studio albums, Surfin' Safari (1962), Surfin' U.S.A. (1963), Surfer Girl (1963) and Little Deuce Coupe (1963)—also appearing on the front cover photos of the Surfin' Safari and Surfer Girl albums and the back cover photo of the Little Deuce Coupe album. Marks departed as a performer after an argument with Murry Wilson, the Wilson boys' father and the band's manager.