The Barbaric Machine Clan Horonderthal (34-35) is of a legendary clan of giant Clockwork Savage Machines which exterminated dinosaurs on the earth 65 million years ago with his violence-inducing Horonden Wave. He battled with the Ancient Engines at that time, with their fight ending up with both sides fossilized within a mountain. Making it his goal, Yogostein manages to find the location with the aid of Drill Banki, only to accidentally free the Ancient Engines instead. But after personally finding the exact location of Horonderthal, Yogostein awakens him from his rest and upgrades him so that his attack can affect Kyoretsu-O. However, in spite of his modern-time upgrades, the Horonderthal became the first to be scrapped by Engine-O G12 with Yogostein taking the Horonderthal's power for himself. His name is from the Japanese word for "extinct" and "Neanderthal".
- Height: 57.6 m
- Weight: 645 tons