n. 篡夺者, 夺取者

[法] 篡位者, 篡夺权者

[ noun ]
one who wrongfully or illegally seizes and holds the place of another
<noun.person>

Usurper \U*surp"er\, 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.

A crown will not want pretenders to claim it, not
usurpers, if their power serves them, to possess it.
--South.