| Nuun Ujol Chaak | |
| Ajaw | |
| Succession: | King of Tikal |
| Reign: | before 657-c.679 |
| Predecessor: | 24th Ruler |
| Successor: | Jasaw Chan Kʼawiil I |
| Spouse: | Lady Jaguar Seat |
| Issue: | Jasaw Chan Kʼawiil I |
| Father: | Kʼinich 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.679), was an ajaw of the major Maya city of Tikal. He took the throne before 657 and reigned probably until his death.[2]