The Serpent

The Serpent was a massive legendary beast located in Tazendeer Ruins on Nekrotafeyo.

Involvement
The Serpent was an Eridian lifeform that guarded the planet's Vault. It was slain by Typhon DeLeon and his wife Leda long before the Vault Hunters reach Nekrotafeyo. According to Typhon, it had several heads much like the mythical beast called the Hydra. Part of its corpse can be seen just outside the Vault of the Serpent.

Trivia
The Serpent is one of  the few Vault creatures that the player witnesses but does not fight.