Theodosius of Kiev or Theodosius of the Caves (Russian: Феодосий Печерский, romanized: Feodosy Pechersky; Ukrainian: Феодосій Печерський, romanized: Feodosiy Pechers'kyy) is an 11th-century saint who brought Cenobitic Monasticism to Kievan Rus' and, together with Anthony of Kiev, founded the Kiev Caves Lavra (Monastery of the Caves).

Theodosius' greatest achievement has been the introducing of the monastic rule of Theodore the Studite in the Monastery of the Caves whence it spread to all the monasteries of the Ukrainian and Russian Orthodox Church.

According to the Primary Chronicle: According to the Life of Theodosius by Nestor the Chronicler:[3] Theodosius has been glorified (canonized) as a saint by the Russian Orthodox Church.

His relics were discovered by Nestor the Chronicler on 14 August 1091, and were found to be incorrupt.

The relics were transferred to the main catholicon (cathedral) of the monastery, and a second annual feast day was established in commemoration of this event.