Marcus Didius Julianus (29 January 133 – 2 June 193) was Roman emperor from March to June 193, during the Year of the Five Emperors.
Julianus had a successful political career, governing several provinces, including Dalmatia and Germania Inferior, and defeating the two Germanic tribes, the Chauci and Chatti. He was appointed to the consulship in 175 along with Pertinax as a reward, before being demoted by Commodus.
Julianus became emperor after winning an auction created by the Praetorian Guard, who had assassinated his predecessor Pertinax. A civil war ensued in which three rival generals laid claim to the imperial throne.