:''For the similarly named Mexican pop singer see Joan Sebastian.
"John Sebastian" (born March 17, 1944) is an American songwriter and harmonica player. He is best known as a founder of The Lovin' Spoonful, a band named to the Rock and Roll Hall of Fame. His tie-dyed denim jacket is prominently displayed there.
John B Sebastian Jr. was born in Greenwich Village in New York City. His father, also named John Sebastian, was a noted classical harmonica player and his mother was a radio script writer. He grew up surrounded by music and musicians, including Burl Ives and Woody Guthrie and hearing such players as Leadbelly and Mississippi John Hurt in his own neighborhood.
thumb|right|Lovin' Spoonful album cover
He came up through the Even Dozen Jug Band and the Mugwumps, which split to form the Lovin' Spoonful and the Mamas and Papas. Sebastian was joined by Zal Yanovsky and popular drummer-vocalist Joseph Campbell Butler in the Spoonful, which was named after a Mississippi John Hurt song.