Behemothe is a huge troll raised in Neriak with his twin brother Leviathann.  Behemothe was born with much higher innate intelligence than Lev, and became a ShadowKnight.  He and his brother were both given their names because of their great size.  It was the Dark Elf high wizard who bestowed these names onto the trolls. 

Behemothe drove to become the best he could be, and trained in the Warrior, Shadow Knight, and Necromancer guilds.  His mentor was Skuhll the Annihilator, a wicked Human Shadow Knight.  The end result of the training was enormous strength, stamina, good agility, and intelligence nearly matching that of Skuhll himself.  The student surpassed the teacher, and furiously spreads the fear of Cazic-Thule the faceless around Norrath.