Wario is said to have been Mario's arch-rival since childhood. Perpetually jealous of Mario's fame and success, Wario's entire life is devoted to one-upping the achievements of his nemesis. Wario's greed and love of material possessions have put him on a never-ending treasure hunt, and he repeatedly travels to faraway lands with the intent to plunder and pillage everything in sight. Wario has a friend named Waluigi, but the rest of his origins are unknown. This is because the Wario character was not created by Shigeru Miyamoto, and thus has not appeared in any "normal" Mario games.

Wario's career has been almost exclusively on the Game Boy. His only SNES appearances were a minor appearance in the obscure Wario's Woods, while on N64 titles he was never anything more than one of many selectable characters in the sports and Party titles.