Legends of the Multi-Universe

is a multiplayer beat 'em up action role-playing game, developed and published for personal computers by Neople, a South Korean subsidiary of Nexon, and originally published by Hangame in 2005. The game was originally released in South Korea as Dungeon & Fighter, then in Japan as Arad Senki, and then published in China by Tencent. In 2014, Neople began an alpha test of a global version of Dungeon Fighter Online using the last English version hosted by Nexon, which has since ended.

DFO is one of the most-played and highest-grossing video games of all time, with over 850 million players worldwide and over $18 billion in lifetime revenue as of December 2021. This also makes it one of the highest-grossing entertainment media products of all time. The game has received Japanese anime and manga adaptations.