The original line-up was Syd Barrett, Roger Waters, Rick Wright, and Nick Mason. Of those, Barrett and Wright have passed away. Barrett left (or was forced out, depending on whose recollection you believe) in 1968, and was replaced by David Gilmour, forming the "classic" 1970s quartet. So, Roger Waters, Nick Mason, and David Gilmour are still alive. All are still touring to some extent; Nick Mason's Saucerful of Secrets is essentially a cover band that plays the early (pre-Dark Side of the Moon) Pink Floyd material.