A.J. Quartermaine is a fictional character from General Hospital, an American soap opera on the ABC network. Born on-screen in 1979 as the only biological child of the iconic Drs. Alan and Monica Quartermaine, A.J. was "SORASed" in 1991, revising his birth year to 1973. The role has been most notably portrayed by the actors Sean Kanan from 1993 to 1997 and Billy Warlock from 1997 to 2003, with a brief return in 2005. Kanan made his on-screen return as A.J. on October 26, 2012, after a 15-year absence. Kanan announced in March 2014 that he would once again be leaving the series, voicing his disappointment over the writing for the character.

Sean Kanan ( né Perelman; born November 2, 1966) is an American actor, producer, and author, best known for his portrayals of Mike Barnes, A. J. Quartermaine, and Deacon Sharpe.