 In the original Edgar Rice Burroughs (qv) novel, Tantor was an old  bull elephant disliked by the denizens of the jungle, Sabor was a  lioness, and Terkoz (presumably "Terk") was a male ape and Tarzans  arch nemesis within the troop. Also, Kerchak murdered Tarzans  family. The producers changed it not only to make him more  sympathetic, but also in recognition of the scientific fact that  gorillas are never that aggressive.