Sergey Gennadiyevich Nechayev (Russian: ?????´? ?????´?????? ????´??) (2 October 1847 – 21 November or 3 December 1882) was a Russian communist revolutionary, often associated with the nihilist movement and known for his single-minded pursuit of revolution by any means necessary, including terrorism and revolutionary terror.
He was the author of the radical Catechism of a Revolutionary.
Nechayev fled Russia in 1869 after having been involved in the murder of a former comrade.
Complicated relationships with fellow revolutionaries caused him to be expelled from the International Workingmen's Association.
Arrested in Switzerland in 1872, he was sent back to Russia where he received a twenty-year sentence and died in prison.
The character Pyotr Verkhovensky in Fyodor Dostoevsky's anti-nihilistic novel Demons is based on Nechayev.
Nechayev is often called a "Bolshevik before the Bolsheviks" and many other Russian revolutionaries were accused of Nechayevshchina by their opponents.
The term was associated with authoritarianism, radicalism and sectarianisn in the time that preceded the Russian Revolution of 1917.