Werewolf Behemoths are Werewolves which have larger and more muscular frame compared to their average counterparts. This often paired with greater abilities. While some of these behemoths appear to have come about naturally, in many cases, they are created by some form of augmentation. For example, Archivist Ernarde's alchemical work and experiments allowed him immediately transform an ordinary member of the Moon Hunter Pack into a behemoth during battle.
In some ways they can be compared to the Argonian Behemoths, which have a similar enhanced body as compared to normal Argonians and can be created by experimentation along with Hist intervention.