Theli (or ThLi, Thele, Teli, TLI, Tali) is the name of the great dragon according to the Sefer Yetzirah. It is said to hold its tail in its mouth, and it is constantly seeking a way to gain entry into heaven. His whole body envelopes the universe. This Serpent sounds similar to the Ouroboros.
Sefer Yetzirah The Book of Creation - Aryeh Kaplan - Red Wheel Weiser 1997
- English translation by W.W. Wescott (1887)