From Longman Dictionary of Contemporary Englishthe beast in somebodythe beast in somebodyCHARACTER/PERSONALITYthe part of someone’s character that makes them experience hatred, strong sexual feelings, violence etc → beast
Examples from the Corpus
the beast in somebody• But see, up on the shelf we had the beast in our fridge too.• Others were fighting to shut the gate, pushing against the sheer bodyweight of the beasts in the gateway.• Then Herb, Junior, had taken his bow and arrow and wounded one of the beasts in the hindquarters. 