1) Offender 2) Usurper 3) Wrongdoer 1) Usurper 
• (n.) One who supplants.
Sup·plan'ter noun One who supplants. 
supplant, supplantation, supplanter 1. Literally, 'To trip up one's heels, to throw down; to put under the sole of the foot, to trip up'. 2. To take the place of; supersede, especially through force or plotting. 3. To remove or uproot in order to replace with something else.supplanter A person who supplants or something that supplants (or supersedes) a pre-existing situation. Related 'foot, feet' units: melo-; ped-; podo-; -pus.