Saita was a massive mutant serpent that lived in the bogs outside of Gilead in the time of Arthur Eld. The snake's name mean "burning venom" in the local dialect; the serpent terrorized the town, slithering into Gilead nightly to destroy crops and eat children.
The snake was eventually slain by Arthur and his knights, though Arthur's sixshooters were irreparably damaged during the battle by Saita's venom.