[Rune Son of Bjarne]

Grima Wormtongue – Probably my favourite, I have no good argument, it just corresponds well with my own view of Grima.
Mouth of Sauron – Definitly a contender, he certainly seem to derive pleasure from others suffering.
Gollum – The obvious choice and I think malice works especially well with the Gollum we encounter in The Hobbit.
Eol – Perhaps, though he clearly dislikes a lot of people, I am not sure I favour him for this title.
Glaurung – Malice is definitely present in Glaurung, but it is almost to mild a term for such wicked creature.
Ted Sandyman – Starts out as just being a stubborn and narrow-minded person, when we first encounter him in the Green Dragon. However there is proper malice in his person, when we meet him again in the Shire after the war has ended. I think that his exchange with Merry and the other hobbits show this clearly.