Kosoy, Kosoi or Cosoi ({{lang-ru|Косой}} meaning slanting, oblique, etc.) is a Russian masculine surname, its feminine counterpart is Kosaya. It may refer to

• Feodosy Kosoy (fl. 1550s), Russian serf-monk
• Laura Cosoi (born 1982), Romanian actress and model
• Stewart Kosoy (1950–2015), American video game designer
• Vasily Kosoy (1421–1448), Grand Prince of Moscow
• Vassian Patrikeyev (Vassian Kosoy), Russian ecclesiastic and political figure and writer

• Mike Green (defensive back)
• Mike Greene
• Mike Greene (actor)
• Mike Green (footballer)
• Mike Green (footballer, born July 1989)
• Mike Green (football player)
• Mike Green (ice hockey)
• Mike Green (linebacker)
• Mike Greenly
• Mike Green (racquetball)
• Mike Green (running back)
• Mike Gregorian
• Mike Gregory (darts)
• Mike Grella
• Mike Grenby
• Mike Gribbon
• Mike Griffin (pitcher)
• Mike Gronstal
• Mike Gruitza
• Mike Gulan
• Mike Gunderloy
• Mike "Gunface" McKenzie
• Mike Gunface McKenzie
• Mike Gunton
• Mike Guy