Complete Monster

"I met him fifteen years ago. I was told there was nothing left. No reason, no conscience, no understanding; even the most rudimentary sense of life or death, good or evil, right or wrong."

—Dr. Loomis, Halloween

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.

The Complete Monster can be recognized by these signs:

The character is truly heinous by the standards of the story, which makes no attempt to present the character in any positive way.
The character's terribleness is played seriously at all times, evoking fear, revulsion and hatred from the other characters in the story.
They are completely devoid of altruistic qualities. They show no regret for their crimes.

Tropes Are Not Good; the Complete Monster can sometimes be indicative of lazy writing. A villain with no redeeming qualities can be viewed as exceedingly simplistic.

Examples: