From the Super Mario Wiki
Hiroji Kiyotake (清武 博二 Kiyotake Hiroji) is a game designer for Nintendo, and also the original designer of Wario. Kiyotake is one of the directors and graphic designers of Super Mario Land 2: 6 Golden Coins and Wario Land: Super Mario Land 3, making him one of the key people for the introduction of the character Wario and the Wario franchise. He was also involved in the development of further Wario games as a designer; for Virtual Boy Wario Land, he acted as a director again. However, for Wario games released after Wario Land 4, his role is mostly limited to the Wario design and advising, according to the staff credits of the respective games. For example, during the development of Wario: Master of Disguise, Kiyotake supervised the numerous forms of disguised Wario designed by SUZAK. In addition, Kiyotake is also the original designer of Foreman Spike from Wrecking Crew.
In the credits of many sports and party titles of the Mario franchise, he is mentioned as one of the character designers.