The Ophiotaurus (meaning Serpent Bull) was an ancient monster that could bring down the gods if it was slain and its entrails burnt. It was a half-cow, half-serpent creature. It was nicknamed Bessie by Percy Jackson, who initially assumed it was female. The Ophiotaurus is currently safe in an aquarium in Olympus built by Hephaestus.
The Ophiotaurus was the creature that Artemis attempted to kill before it could turn to the Titans' side and defeat the gods. Percy first meets him trapped in a net and, being unaware that the creature was actually a male, nicknames him Bessie. Thanks to the Hippocampi and Percy the monster was freed. The Ophiotaurus was the center of the General's plan to bring down the gods by having Thalia Grace call the beast to her, kill it, then sacrifice its entrails as a tribute. However it was Percy, not Thalia, that the Ophiotaurus follows around. This is due to Percy's rescue, and the monster's belief that Percy is its protector. Grover later takes it to Olympus, and Percy sacrifices the Nemean Lion's Pelt to ensure they arrive safely. Deciding to allow it to live after a heart filled testimony by Percy, Poseidon and Hephaestus made a sphere-shaped aquarium for it on Mount Olympus, after Zeus refuses to let Poseidon harbor him under the sea as a "bargaining chip." 2b1af7f3a8