Lee M. Ranaldo (born February 3, 1956) is an American singer and guitarist, probably best known as a co-founder of the rock band Sonic Youth.

Ranaldo was born in Glen Cove, Long Island, New York, and graduated from Binghamton University. He has three sons, Cody Linn Ranaldo, Sage Ranaldo and Frey Ranaldo and is married to the experimental artist Leah Singer, with whom he has performed many live installation pieces with improvised music.

Among Ranaldo's solo records are Dirty Windows, a collection of spoken texts with music, Amarillo Ramp (for Robert Smithson), pieces for the guitar, and Scriptures of the Golden Eternity. His books include Bookstore, Road Movies, and Jrnls80s (published by Soft Skull Press). A full-length book of writings on Moroccan travels and music, as well as a book of new poems, Lengths & Breaths, are out now. Recent visual work has been included in exhibitions at the Hayward Gallery in London, the Sydney Museum of Contemporary Art and Mercer Union in Toronto.

Ranaldo has produced albums for artists including Babes in Toyland, You Am I, Deity Guns, and Dutch art rock-ensemble Kleg. He has edited a volume of tour journals from the 1995 Lollapalooza Tour written by Thurston Moore, Beck, Stephen Malkmus, Courtney Love, and others. Ranaldo has also worked with jazz drummer William Hooker on improvised music, and reading and improvising poetry.

In 2004, Rolling Stone ranked Ranaldo and Thurston Moore, of Sonic Youth, the 33rd and 34th best guitarists of all time. Their playing style is very innovative and they both use a large variety of extended techniques, such as their 3rd Bridge screwdriver technique.

Ranaldo usually uses Fender Jazzmaster and Telecaster Deluxe electric guitars, with radically altered tunings, and modifications.