| Nuun Ujol Chaak | |
| Ajaw | |
| Succession: | King of Tikal |
| Reign: | before 657-c.679 |
| Predecessor: | 24th Ruler |
| Successor: | Jasaw Chan K'awiil I |
| Spouse: | Lady Jaguar Seat |
| Issue: | Jasaw Chan K'awiil I |
| Father: | K'inich Muwaan Jol II |
| Birth Date: | before 657 |
| Birth Place: | Tikal |
| Death Date: | c.679 |
| Death Place: | Tikal |
| Signature: | Nuun Ujol Chaak.svg |
Nuun Ujol Chaak[1] also known as Shield Skull and Nun Bak Chak (born before 657-c.679CE), was an ajaw of the major Maya city of Tikal. He took the throne before 657 and reigned probably until his death.[2]