Answer
John Sebastian is not a member of any other bands. He was a founding member of the Lovin' Spoonful, and has been the only constant member of the band since its inception in 1965. Sebastian is best known for his work with the Lovin' Spoonful, and has written and performed many of the band's most popular songs, including "Do You Believe in Magic," "Daydream," and "Summer in the City."