Joe Klein, Bill Russell, KC Jones, Charles E. Smith IV, Quinn Buckner, Jojo White, Charles Scott, Alton Lister, Shaq, Gary Payton, Ray Allen, Vin Baker, KG are some who have played in the Olympics.
Never used pro players until 1992, so NCAA players actually tried out for the Olympic teams.
So, the answer is Larry Bird is the only current Celtic who played in an Olympic game.