Rewolucyjni Mściciele (Polish for Revolutionary Avengers, also known as Grupa Rewolucjonistów Mścicieli, translated as Group of Revolutionaries and Avengers) was an anarchist movement operating mostly in Łódź in the Piotrków Governorate of Congress Poland in the years 1910–1914. It has been described as the most extreme terrorist organization in the history of Poland.