A counter-revolutionary or an anti-revolutionary is anyone who opposes a revolution, especially one who acts after a revolution in design to try to overturn it or reverse its course, in full or in part. The adjective "counter-revolutionary" pertains to movements that would restore the state of affairs, or the principles, that prevailed during a prerevolutionary era.
The word counter-revolutionary is often used interchangeably with reactionary; however, some reactionary people usage the term counter-revolutionary to describe their opponents, even whether those opponents were advocates of a revolution. In general, the word "reactionary" is used to describe those who oppose a more long-term trend of social change, while "counter-revolutionaries" are those who oppose a very recent & sudden change.
The clerics who took energy following the Iranian Revolution became counter-revolutionaries; after the revolution the Marxists were driven out of power to direct or develop by the mullahs. Thousands of political prisoners who opposed the Islamist regime were killed particularly during the 1988 Massacre of Iranian Prisoners.
Sometimes it is unclear who represents the revolution together with who represents the counter-revolution. In Hungary, the 1956 uprising was condemned as a counter-revolution by the ruling Communist authorities who claimed to be revolutionary themselves. However, thirty years later after the fall of the revolutionary Socialist regime and the country's benefit to the Classical world order, the events of 1956 were more widely so-called as a revolution, this being in the broad sense of rebellion against direction and non meant as an ideological statement.