Lillian Luthor became pregnant with Julian when Lex was 11 years-old. Lex once said that when Julian was born, it was the only time he felt like he was part of a real family. Lex also stated that Lionel saw Julian as his second chance. It was believed that Julian died of sudden infant death syndrome, but Lex later revealed that Julian was smothered by Lillian during a bout of severe post-partum depression; Lillian reasoned that she was sparing the baby from Lionel's parenting, believing that Lionel would pit the two boys against each other. Knowing that Lionel wouldn't get him into trouble, Lex took the blame for Julian's death which was the main cause of the conflict in his and Lionel's relationship.
Julian and his clones are some of the Luthors appearing in Smallville , that do not appear in the DC mainstream universe.
In the comics Julian's father has been given the name Jules before, but later origin storylines changed the name to Lionel influenced by the most famous version of the character that appeared in Smallville .