Conan Meriadoc (modern Breton Konan Meriadek, Latin Conanus Meridiadocus; died ca. 395) was the legendary 4th century founder of the house of Rohan and legendary leader of the earliest British settlement in Armorica.

According to medieval Welsh sources (including Geoffrey of Monmouth), Conan Meriadoc was the cousin (by marriage) of Macsen Wledig and nephew of Octavius. After he rebelled against Octavius, Macsen summoned him before departing to establish himself as Roman emperor, and gave Conan Armorica to rule as his own kingdom. Conan then led the settlement of Armorica by Welsh mercenaries and gave it the name of Brittany, or "Little Britain".

In the Cornish miracle play Beunans Meriasek, Conan is a kinsman of St Meriasek who tries (unsuccessfully) to dissuade Meriasek from pursuing a religious life.