The Chiller is a one-shot human villain who appears in the complete Sonic story, The Frozen Zone. As his chosen monniker implies, the Chiller is an expert in weather control and cryogenic technology. He had established himself in the Pleasant Zone and had created a Chilling Machine that could alter the temperature of the zone. The villagers had mocked his ideas and deemed them too dangerous, but the Chiller took his revenge by casting the Pleasant Zone into perpetual winter and sending out his Chill-Bots to freeze the populace. When Sonic and the Freedom Fighters came to investigate the Pleasant Zone, the Chiller's robots attacked them. When Sonic broke into Chiller's lab, the Chill-Bots froze his feet so he couldn't move. The Chiller then took the time to explain his plans in intricate detail (in classic supervillain fashion) which gave Sonic time to vibrate his feet at high speed and break free of the ice. He then thawed out his frozen friends and reversed the Chiller's machine, warming the Pleasant Zone and freeing the villagers. The Chiller admitted we wasn't very good at being a bad guy, and so he used his scientific prowess to help the Pleasant folk. He re-purposed his Chill-Bots into Mop-Bots so that they could clean up the zone. It is never explained how he ended up on Mobius.
The Chiller has made no appearances since Issue 40.