The Complete Monster is the most depraved of all characters; a villain utterly lacking in redeeming features. Trying to put a value on the evilness of a Complete Monster is like calculating the credit score of Bill Gates: it's a moot point.
Or, anyway, that is how the character is presented in the story. The character is a bad guy, full stop. The author has not taken the character through any actions toward redemption, or at least any that stuck.
Complete Monster has been suggested to play 7 roles. Click below to see other actors suggested for each role, and vote for who you think would play the role best.