Alan Rickman steals nearly everything he's in, IMO. He's the only reason Costner's Lame Robin Hood was any good. And of course...
"By Grabthar's hammer, by the sons of Worvan, you shall be avenged!"
Edit: If you get a chance, catch the HBO movie "Something the Lord Made". Rickman plays a heart doctor who pioneered a 'shunt' surgery to fix the hearts and the lives of blue babies. He's great in that movie, and maybe even better is Mos Def who played his assistant. Powerful movie all the way around.