"Wario (ワリオ) is a fictional Nintendo video game character originally designed by Hiroji Kiyotake. Wario was designed as another antagonist to Mario (besides Bowser), and first appeared in the 1992 Game Boy title Super Mario Land 2: 6 Golden Coins as the main antagonist and final boss. Since that time, Wario has developed into the protagonist and antihero of the Wario Land and WarioWare series, spanning handheld and home console markets, in addition to his numerous appearances in spin-offs in the Mario series. He is voiced by Charles Martinet, who also voices Mario, Luigi, Waluigi, Baby Mario and Baby Luigi."
Source: Wikipedia, "Wario", available under the CC-BY-SA License.