Dr. Ovi Kintobor
From Sonic Retro
Robotnik's original, good natured self. He was turned into Robotnik when using the ROCC or R?? Orbital Chaos Compressor, and spilled (?) onto the machine. He also happened to be holding a rotten egg in his hand, this ensuring his transformation into a figurative rotten egg.
Little known fact: Ovi is the latin word for egg. Coincidence? Nah.