A possible inspiration for Wario first appeared in the 1985 game Wrecking Crew in the character of Spike, a construction foreman.[1] Although he bears a slight resemblance to Spike, Wario did not debut until 1992. The first named appearance of the character occurred in the game Super Mario Land 2: 6 Golden Coins. He was designed by game artist Hiroji Kiyotake.[2] Wario's design arose from Super Mario Land's design team's distaste of making a game based around someone else's character. The creation of Wario allowed them a character of their own to "symbolize their situation".[1]

Wario is portrayed as a caricature of Mario; he has huge, muscular arms, short stubby legs, a large, pointier, zig-zagging moustache, and a bellicose cackle. He also wears a plumber outfit with a yellow and purple color scheme.[3] The name "Wario" is a portmanteau of "Mario" with the Japanese adjective warui (悪い?) meaning "bad"; hence, a "bad Mario" (further symbolized by the "W" on his hat, an upside down "M").[4][better source needed] Official Nintendo lore states that Wario was a childhood rival to Mario and Luigi who became jealous of their success.[5] Voice actor Charles Martinet, who has voiced Mario since 1995, is also the voice for Wario. During the audition for the part, Martinet was told to speak in a mean and gruff-sounding tone. He described voicing Wario as a looser task than voicing Mario, since Mario's speaking manner and personality are more free-flowing, rising from the ground and floating into the air, while one of Wario's cornerstones is jealousy.[6] Starting with Wario Land: Super Mario Land 3, Wario experiences rejuvenating effects from garlic in a similar manner as Mario is powered up by mushrooms. Wario often uses bombs, as seen in Wario Land: Super Mario Land 3, Wario Blast and Mario Kart: Double Dash!!. The WarioWare series prominently uses bombs as a visual motif to represent the time limit.

In video games in which Wario makes a cameo appearance, he is often portrayed as a villain. However, the development team for Wario Land: Shake It! stated that he was not really a villain, and they did not consider him one during development. They focused on his behavior, which alternates between good and evil.[7] Etsunobu Ebisu, a producer of The Shake Dimension, considered Wario to be a reckless character, who uses his strength to overwhelm others. Tadanori Tsukawaki, the design director of The Shake Dimension, described Wario as manly, and said he was "so uncool that he ends up being extremely cool". Because of this, he wanted Wario to act macho rather than silly and requested that the art designers emphasize his masculinity.[8] Wario was chosen as the star of the WarioWare series because the developers felt he was the best character for the franchise because he often acted stupid