1) Coup leader 2) Coup participant 3) French word used in English 4) Offender 5) One in a coup group 6) One taking something forcibly 7) One who expropriates 8) One who seizes power 9) One who takes over by force 10) Power grabber 11) Power-grabber 12) Seizer like Caesar 13) Successful rebel 14) Supplanter 1) Deposer 2) Supplanter 
An usurper is an illegitimate or controversial claimant to power, often but not always in a monarchy. This may include a person who succeeds in establishing himself as a monarch without inheriting the throne or any other person exercising authority unconstitutionally. A person who takes the power of the country for himself or herself at the expens...
• (n.) One who usurps; especially, one who seizes illegally on sovereign power; as, the usurper of a throne, of power, or of the rights of a patron.
One who assumes the right of government by force, contrary to and in violation of the Constitution of the country.
HMS Usurper was a British U Class submarine of 540 tons displacement launched and sunk during the Second World War. HMS Usurper was powered by two Davey Paxman diesel engines providing a top speed of 11 knots surfaced and two electric motors providing a top speed of 9 knots submerged. She carried a complement of 31 was armed with one 3 inch gun; th...
[n] - one who wrongfully or illegally seizes and holds the place of another
usurper A person who wrongfully or illegally seizes another's place, authority, or possessions unjustly; in a manner contrary to moral law or to justice.
[Wuthering Heights] a person who wrongfully takes a possession or position.
supplanter noun one who wrongfully or illegally seizes and holds the place of another
[Difficult words] one who wrongfully seizes and holds the place of another