GRUKAG
The Chief Advisor to the Orcish Leader, Grukag has it out for Mack. Grukag has successfully kicked him out of the Orcish Kingdom in the Yin Sloth Jungles, but really wants him dead.
Grukag loves power, and is great at politics. He also loves torture, and nothing would make him happier than a chance to torture Mack.
Picture by the phenomenal Grzegorz Rutkowski.