"Lee Mark Ranaldo" (born February 3, 1956) is an American musician, singer-songwriter, guitarist, writer, visual artist and record producer, best known as a co-founder of the alternative rock band Sonic Youth. In 2004, Rolling Stone ranked Ranaldo at number 33 on its "Greatest Guitarists of All Time" list. In May 2012, Spin published a staff selected top 100 list, ranking Ranaldo and his Sonic Youth bandmate Thurston Moore together at number 1. Ranaldo was born in Glen Cove, Long Island, studied art and graduated from Binghamton University and is married to the experimental artist Leah Singer. Ranaldo started his career in New York in several bands, and joined the electric guitar orchestra of Glenn Branca.

In 1981, he and David Linton briefly joined the band Plus Instruments formed by Truus de Groot. With this line-up they recorded the album February - April 1981, released on the Dutch Kremlin label.

After the release of the album, Ranaldo left the band and started Sonic Youth with Thurston Moore and Kim Gordon. Ranaldo released his first solo album, From Here to Infinity in 1987.