J Mascis (/ˈmæskɪs/ MASS-kiss; born Joseph Donald Mascis, Jr. on December 10, 1965) is an American musician, best known as the singer, guitarist and songwriter for Dinosaur Jr. He was ranked number 86 in Rolling Stone magazine's list of the "100 Greatest Guitarists of All Time", and in 2012, he was ranked 5th in Spin's list of the 100 greatest guitarists of all time.