Mithras was the god of Roman warriors, the legion, and empire. He had a secret cult of warriors and was popular in the legions. He was one of the gods who replaced Athena as a war deity. He was originally a Persian god before being adopted by the Romans.
He was born from the rock, where he emerged fully grown and holding his dagger and torch. He was famous for slaying a sacred bull.
There are seven rites of passage to gain entrance into the cult of Mithras. There are also seven levels of membership, the top level being the pater, who Annabeth Chase meets. If a person is an unbeliever, then they must die by fire or dagger.
Mithras' symbols are the torch and dagger, which one can be initiated into the cult with.
Aphrodite mentions Mithras as one of the deities that replaced Athena. Later, Annabeth Chase encounters a dozen ghosts, similar to the Lares of Camp Jupiter, in their sacred cavern of Mithras, when she follows the Mark of Athena, an owl. The ghost realizes Annabeth's disbelief and asks her to choose her path of death, or else Mithras will choose it for her.
However, Annabeth guesses their secrets: the rites of passage, levels of membership, and the ordeals. She bluffs that she is the 'magna mater' of the sisterhood of the child of Athena. The ghosts try to kill her, but Annabeth reminds them that they are dead. The pater says that Mithras will do it for them, and the statue on the altar begins to glow. The ghosts say that they cannot allow her to pass, as the weaver told them that she must be killed. She notices that the cavern is old and that the ceiling has cracks. Annabeth declares that she has power over the very stones, and strikes the capstone with her dagger. The Celestial Bronze blade shatters the ceiling. The pater scoffs at her until suddenly the room shakes and the ceiling collapses on the altar and the pater. She slams with all her strength on the blocked entrance, and the bricks give way. She lunges out of the hole and finds herself falling into darkness.
Mithras was again referred to when Apollo remembered the type of monster protecting Nero's Fasces and remembered it to be the leontocephaline. Mithras was stated by Apollo to have been incredibly secretive that during his time in Olympus as a Roman God, He, Jupiter and the other Olympians barely knew anything about him. Luguselwa mentions that while a lot of Roman officers worshipped Mithras back in the day, she had never taken to the Persian gods. Lu calls Mithras' cult an elite members-only society of which the emperor was an automatic member, explaining how Nero had found the leontocephaline in the first place.
Mithras was stated to have had a Scepter of Immortality that the leontocephaline was originally guarding and that the monster itself was created by him for that purpose. The Scepter itself was stated to have gone missing eons ago.
- The word "mitra" in Sanskrit, Hindi and many other Indian languages, means 'friend'.
- The word "mehr", derived from Mithra, means 'love' in Persian and many Iranian languages.