Weyoun is a Vorta, a race from the Gamma Quadrant. They have been adapted into the Dominion hiearchy as administrators.
The last Weyoun clone was killed by Elim Garak, Kira Nerys and their coup. Although Weyoun can be cloned again, the possibility of Weyoun being resurrected is slim, due to victory of the United Federation of Planets and its allies over the Dominion.