== Baggrund ==
Julian var søn af Julius Constantius (romersk [[Consul|konsul]] i [[335]] og halvbror af kejser [[Konstantin den Store]]) og dennes anden kone Basilina, som var af græsk herkomst.<ref>{{cite book |last = Norwich |first = John Julius |title = Byzantium: the early centuries |url = https://archive.org/details/byzantium00norw |publisher = Knopf |year = 1989 |page = [https://archive.org/details/byzantium00norw/page/83 83] |isbn= 978-0-394-53778-8 |quote = Julius Constantius...Constantine had invited him, with his second wife and his young family, to take up residence in his new capital; and it was in Constantinople that his third son Julian was born, in May or June of the year 332. The baby's mother, Basilina, a Greek from Asia Minor, died a few weeks later... }}</ref> Begge Julians forældre var kristne. Hans fars forældre var kejser [[Constantius Chlorus]], den eneste hedenske byzantinske kejser,<ref>{{cite book |last = Bradbury |first = Jim | author-link=Jim Bradbury |title = The Routledge companion to medieval warfare |url = https://archive.org/details/routledgecompani00brad |publisher = Routledge |year = 2004 |page = [https://archive.org/details/routledgecompani00brad/page/n63 54] |isbn = 978-0-415-22126-9 }}</ref> og dennes anden kone, Flavia Maximiana Theodora. Hans mormors navn er ukendt; men hans morfar hed Julius Julianus og var [[Prætorianergarden|prætorianerpræfekt]] i øst under kejser [[Licinius]] fra [[315]] til [[324]].<ref>Jones, Martindale og Morris (1971) ''Prosopography of the Later Roman Empire'', 1. bind, s. 148 og 478–479, Cambridge</ref>
Filosofi