A self-coup (Spanish autogolpe) occurs when a leader who already holds power, usually after winning an election, uses force or the threat of it to dissolve or bypass the other branches of government. Nancy Bermeo counts such "executive coups" among the forms of democratic breakdown that have been becoming less common (Bermeo 2016).
Classic example: Peru, 1992
On April 5, 1992, President Alberto Fujimori announced the "temporary closure" of the opposition-controlled Congress, set up a "National Reconstruction Government," and reorganised the judiciary, while the armed forces sent tanks and soldiers into the streets of Lima (Andina). See the full entry on Peru under Fujimori.
Related concepts
Contrast the self-coup with the gradual executive aggrandizement that Bermeo found has become more common, and with autocratic legalism.