This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. One who usurps.

n. One who usurps; especially, one who seizes illegally on sovereign power.

n. One who usurps; one who seizes power or property without right: as, the usurper of a throne, of power, or of the rights of a patron.

n. one who wrongfully or illegally seizes and holds the place of another

"I have no recollection of ever having said or written the word "usurper," but if the foo s**ts, wear it."

offender    wrongdoer   

usurpress   

claim jumper   

impostor    invader    tyrant    tormentor    oppressor    interloper    plunderers    despot    robber    blasphemer