sworn enemy

In The Next Mutation, Shredder is still the Turtles' sworn enemy.

"It is that Catterson has made it public that the sheriff is his sworn enemy."

Elomire is his sworn enemy: an esthete holding out for the highest standards in a civilization where the lowest common denominator is increasingly prized.

Bellarius says that Votarius is his sworn enemy.

He has an evil megalomaniac cousin, Zantafio, who is his sworn enemy but bears a strong physical resemblance to him.

Selvi is the sister of his favorite henchman who now becomes his sworn enemy and joins the enemy gang.

The Smurfs' sworn enemy, Gargamel, creates a potion that turns him into a Smurf, his plan being to infiltrate their village and destroy them.

He thwarts a rival or we kill his sworn enemies for him.

Here with a friendly hand on his shoulder stood Videssos' sworn enemy, the man Avshar named master.

He says his sworn enemies are "authority, depressing laws, the return of the moral order, nuclear power, any form of political power."