Sirzechs Lucifer

Sirzechs Lucifer, formerly Sirzechs Gremory, is Rias Gremory's older brother and is known as the Crimson Satan. He leads the Four Great Satans who rule the Underworld under the title "Lucifer." He is married to Grayfia Lucifuge, and they have a son, Millicas Gremory.