Wikipedia
The Monarchomachs were originally French Huguenot theorists who opposed monarchy at the end of the 16th century, known in particular for having theoretically justified tyrannicide. The term was originally a pejorative word coined in 1600 by the Scottish royalist and Catholic William Barclay (1548–1608) from the Greek μόναρχος (monarchos "monarch, sole ruler") and μάχομαι ("makhomai" the verb meaning "to fight"), meaning "those who fight against monarchs".
Born out of the context of the French Wars of Religion, they were most active between 1573, a year after the St. Bartholomew's Day massacre, and 1584. The Monarchomachs pleaded in favour of a form of " popular sovereignty". Arguing for a sort of contract between the sovereign and the people, they have been considered as the precursors of social contract theories.