- Name: Zangyaku-seijin (ザンギャク星人, Brutal Alien)
- Classification: Kaiju
- Homeland: Planet Zangyaku
- Chojin Kyodo: 200,000 Power(?)
- Favorite Technique: Southpaw Gun
- First Appearance: Manga Chapter 9, Anime Episode 14
- Seiyu: Daisuke Gori
Zangyaku-seijin is an alien whose father was killed by Kinnikuman while trying to take over the Earth. He has a gun for a hand and speaks in Hichiku dialect. He hijacks a bus with Kinnikuman, Meat, Mari, and the school children and demands to fight Kinnikuman. Kinnikuman refuses until he lets the children and Mari go (Meat stays behind on his own accord). He is defeated when Kinnikuman's Kinniku Flash causes the bus to explode. Kinnikuman gets good press over this fight (the headlines reading "Kinnikuman Miraculously Saves the Day"), but the children are ungrateful because they have to walk to school now thanks to him. His appearance also marks the debut of Detective Akaiwa. In the anime, he is also referred to as The Brutal Alien. Nachiguron acts as his his minion.