Kelly was born in Saugus, Massachusetts on October 2, 1932. He graduated from Emerson College with a bachelor's degree and received a masters degree in play-writing from Yale University. His first stage play was Widow's Walk, published in the 1960s. At the same time, three of his plays opened: A Darker Flower at New York's Pocket Theatre, The Trunk and All That Jazz at Boston's Image Theatre, and Die Blum in Germany. He wrote over three hundred plays, which have been performed by the Royal Court Rep, the Studio Theatre, Manhattan Theatre Club, Los Angeles Actor's Theatre, the Aspen Playwright's Festival, and the Seattle Repertory Company. Additionally, Kelly was a drama critic and journalist in Phoenix, Arizona (1957–1967) and was particularly noted for the broad scope of his work, which covered everything from mysteries to musicals to serious drama. He was also a screen and television writer (1968–1978). In 1995, he became a member of the College of Fellows of the American Theatre. On December 7, 1998, Tim Kelly died suddenly of a brain hemorrhage (age 61) in his Hollywood home. A Tim Kelly Collection has been established at the University of Wyoming's American Heritage Center. Emerson College has twice honored him for his "contributions to the field of playwriting."