Since I wrote my thesis on Spanish film, I have to chime in here. The classic actor Fernando Fernan Gomez has to be mentioned, and I really enjoy the work of Eduardo Noriega (you have to see "Abre los ojos"--he puts Tom Cruise's performance in the US remake to shame). But if we judge on looks, my favorite without a doubt is Penelope Cruz, and she's not a bad actor, either.