vendettist
/ˌvɛndɪˈtɪst/Definitions
1. noun
A person who engages in a vendetta, often involving prolonged and bitter revenge.
“The wealthy businessman was accused of being a ruthless vendettist who would stop at nothing to eliminate his competitors.”
2. adjective
Characterized by or given to a vendetta, often in a violent or revengeful manner.
“The vendettist tactics of the mafia led to a violent crackdown by law enforcement.”