Ah sorry Galedeep, just saw a few posts that were just pictures so thought that was ok. Let's try again...
Prince John and
Sir Hiss: 
I'm sure most people have seen
Robin Hood, and realise that these two are not the best villains in the sense of actually achieving anything. They're just hilarious in their antics, and Robin Hood always somehow manages to outwit them.
They are certainly villainous, taxing the whole of Nottingham, and eventually putting virtually the whole town in prison (including Friar Tuck, who they plan to execute). However, their plans to capture Robin Hood always fail, and he ends up robbing them on several occasions. Eventually, they get what they deserve when King Richard returns from his Crusades and sees what they have done to Nottingham.
The Headless Horseman

An awesome villain, utterly twisted thanks to Tim Burton's genius. After terrorising the inhabitants of
Sleepy Hollow for several weeks, a treacherous plot involving wills, inheritance, and money is discovered, with the Headless Horseman being used as the main tool to implement the plan, by executing anyone who might stand in the way.
His sword skills are awesome, he's almost unstoppable, and he definitely has style. Really all he wants is to be free to rest, after being resurrected and forced to obey whoever holds his decapitated skull.
Magneto(take your pick)

An extremely fearsome and powerful villain, Magneto will allow nothing to stand in his way to achieve what he wants. One of the most powerful mutants, there are few who can stand up to him. He views humans as expendable, and will happily kill humans in order to protect a mutant; he attempts to destroy humanity in order for the superior mutant race to survive, and is narrowly thwarted by Xavier and the Xmen.
Ian McKellen is perfect for his role in the film, and portrays his character perfectly.