bad actor

Short definition from Wiktionary

Noun

1. 1
   An individual or entity with a prior criminal conviction, or who has been sanctioned by the court or regulator.
2. 2
   A person with malicious intent.
3. 3
   An ill-intentioned, mean, badly behaved or ill-tempered person.
4. 4
   Used other than figuratively or idiomatically: see bad, actor.