You likely know the Mystery Dungeon games from Pokémon. Maybe the Chocobo one?
However, it's a pretty random character that started off the whole thing. The merchant Torneko from Dragon Quest IV decided to start dungeon crawling one day, giving us Torneko no Daibōken: Fushigi no Dungeon on Super Famicom. The game was popular enough to launch a whole set of licensed spinoffs and Torneko even got two more games out of it.
All in a day's work.
