Saddam Hussein killed terrorists. He was the stable force in the middle east until the Americans screwed it up.
He killed SOME terrorists who challenged his rule, but he supported other terrorist groups that were, for political and ideological reasons, close to him. Obviously the Iraq War should not have taken place the way it did, but to act as if Saddam Hussein was some great, anti-terror crusader is to ignore reality.
http://www.politifact.com/truth-o-meter/statements/2016/jul/07/donald-trump/was-saddam-hussein-good-killing-terrorists-donald-/