Slagar the Cruel from Redwall

The Cruel, the Slaver, the Lord of Double-Dealing, Lunar Stellaris, they're all names for the same revenge-craving fox. (Purposefully leaving out one name in particular due to spoilers)
Slagar from Mattimeo, in the book series Redwall (this version being from the cartoon)
He's apparently also referred to as "Mousedeath" according to the wiki