bad actor

Noun

 * 1)  Individual or entity with the prior criminal conviction, or who has been sanctioned by the court or regulator.
 * 2)  A person with malicious intent.
 * 3)  Ill-intentioned, mean, ill-tempered person.
 * 1)  A person with malicious intent.
 * 2)  Ill-intentioned, mean, ill-tempered person.

Usage notes
In the legal sense "bad actor" is also used in financial regulations, ex. not allowing such people or companies to participate in certain regulated processes, or to take advantage of certain privileges. Often used as opposed to "an upstanding citizen".