The Syrian nobleman Gaius Julius Avitus Alexianus (c.155-217) is not among the most famous Romans, and yet he was one of the most important officials during the reigns of the emperors Septimius Severus (193-211) and Caracalla (211-217). He was the husband of Severus’ sister-in-law, Julia Maesa; the couple had two daughters, Julia Soaemias and Julia Mamaea, who were to become the mothers of the emperors Heliogabalus and Severus Alexander.
Alexianus’ own career is quite interesting. After the usual military offices, he was responsible for the food supply of Rome, and may have played a role during the coup of Severus. He appears to have taken part in the campaign against Pescennius Niger and the Parthian Empire as commander of the Fourth Legion Flavia Felix, and was made governor of Raetia. After his consulship, his career came to a standstill, probably because it was obstructed by Plautianus; after his fall, he occupied several other prefectures and governorships. There’s more about him here.