Yaponchik () is a nickname widely known in the Russian-speaking criminal world. It may refer to:
Mishka Yaponchik, Odesa robber turned Soviet military leader (1881–1919) Fictional character in Russian TV series The Life and Adventures of Mishka Yaponchik, only loosely based on the real-life thug Vyacheslav Ivankov, Russian mafia boss (1940–2009)
Literally, yaponchik means "little Japanese", though none of the two above had any Japanese ancestry.