From the Super Mario Wiki
Kevin Bayliss is a former Rare employee who worked as a graphics and character artist for many of Rare's franchises since he was hired in 1987, including Donkey Kong Country and Diddy Kong Racing. In Donkey Kong Country, he was in charge of the redesign of Shigeru Miyamoto's original concept of Donkey Kong to his current 3D appearance, as well as creating Diddy Kong and the basic Kremling idea. In addition to art-related work, Bayliss also voice acted for several games. He left the company in 2005 to work as a freelance artist.