John Constantine was born in Liverpool, England. His identical twin died in the womb and his mother died giving birth to John, who then grew up with a neglectful and abusive father. Constantine began practicing magic and performed his first spell as a child, which was to dispel himself of his childhood innocence. When he became an adult, Constantine moved to London where he spent time as the lead singer of his punk rock band, "Mucous Membrane", before a failed exorcism forced him to become a private investigator specializing in magic and the occult. He was once romantically involved with fellow magician Zatanna, was an infrequent ally of Swamp Thing and was a founding member of the Justice League Dark. Constantine is the keeper of the House of Mystery.
Constantine is an expert in various forms of magic, from subtler tricks that allow him to manipulate his enemies and create his own luck, to more elaborate spells which allow him to harness pyrokinesis, necromancy, illusions and even teleportation. On occasion he has even been able to access other planes of reality and even alternate universes. Constantine is also resistant to telepathy and mind control, and is barely capable of hand-to-hand combat. A blood transfusion from the demon, Nergal, is believed to have mildly enhanced his healing and slowed his aging.
He is frequently seen wearing a brown trench coat along with a red tie and a white shirt, while his hair is short and blonde. Constantine was originally created to resemble rock musician, Sting.
- Constantine is one of the only characters from DC's mature imprint Vertigo to appear in Justice League Action. Thusly, many elements of his character are omitted or merely implied.
- When he appears 10-years-old in "Trick or Threat" (and in his earlier appearance) Constantine is seen constantly with a rock candy stick in his mouth in a veiled reference to the character's chain-smoking habit from the comic books.