Mithras or Mithra was a Sun god, probably originating in Persia, whose worship became widespread in the Roman Empire, from the 1st to 4th centuries AD, especially among soldiers. Mithraism was a serious competitor to early Christianity, and was completely suppressed after pagan religions were outlawed in AD 383.
Modern historians conjecture, however, that victorious Christianity absorbed some elements of Mithraism, such as addressing a priest as "Father" which did not exist in early Christianity. Elements of the uniforms and accoutrements for the Pope and other Catholic priests borrowed from Mithraic priests, including a crown called a mitre. The 25th of December apparently was considered Mithras' birthday before it was reassigned to Jesus.
As the secretive Mithraists left behind no writings, it is unclear whether Mithras was the subject of adventurous stories the way Zeus and the Olympians were. Ancient paintings and sculptures survive, and appear to show Mithras being born full-grown from solid rock, and later slaughtering a bull to fertilise the Earth with its blood.
Mithras the Bull-Slayer remained a prominent member of the Roman pantheon well into the 21st century. He was sometimes depicted along with Jesus Christ, another member of the Roman pantheon. In Polisso, Dacia, Prefect Sesto Capurnio had a painting in his office, showing the two fighting off a demon together. Generally, however, Mithras was depicted in a more impressive light than Jesus.