Wonder Boy in Monster World, known in Japan as Wonder Boy V: Monster World III, is a side-scrolling action RPG originally developed by Westone and published by Sega for the Mega Drive/Genesis in 1991. It is the fifth game in the Wonder Boy series and the third game in the Monster World sub-series, following Wonder Boy in Monster Land (Super Wonder Boy: Monster World on the Japanese Sega Mark III) and Wonder Boy III: The Dragon's Trap (Monster World II: Dragon no Wana on the Japanese Game Gear). It was also the last Wonder Boy game that was given an official English release, until the Wii Virtual Console release of Monster World IV in 2012.