Anatoly Onoprienko (Анатолій Онопрієнко) (born 1959) is a Ukrainian serial killer. He is also known by the nicknames The Terminator and Citizen O. When police arrested the 37-year-old former forestry student on April 16, 1996, they finally ended Ukraine's worst killing spree.

Anatoly, a native of Zhytomyr, was carrying a hunting rifle that matched the murder weapon in several of the killings and had jewellery and video equipment which may have belonged to some of his victims. While in custody he immediately confessed to eight killings between 1989 to 1995. At first he denied other charges, but soon admitted to being the murderer of 52 victims in a six-year killing spree. Once in custody, the ex-forestry student claimed that his killing spree was commanded by "inner voices" he kept hearing.

A manhunt was launched across Ukraine in March, 1996, after eight families were brutally murdered in their homes. Most of the victims were in remote villages in the Lviv region near the border with Poland. There were so many killings in one village that army troops were sent to patrol the streets.

The killings followed a set pattern. "The Terminator" chose an isolated house, shot everyone inside including any children, and torched the place. He would also kill any witness unlucky enough to cross his path during his murderous rampages. The first to die were a family of four in Bratkovichi. Another family of five and two witnesses were killed not long after in the same village. When police imposed a security cordon around Bratkovichi, "The Terminator" moved to other villages where he continued his serial slaughter.