Born Publius Aelius Hadrianus (76-138 CE) to a well-established family with old roots in Hispania, Hadrian was related to Emperor Trajan through his father, who was a maternal cousin of Trajan's. Trajan did not officially designate an heir before he died, though his wife Pompeia Plotina claims that Trajan named Hadrian his successor just before his death.

Hadrian travelled extensively during his reign, visiting nearly every province in the Roman Empire. He attempted to turn Athens into the Empire's cultural capital, and had a Greek lover named Antinous. Hadrian also spent a lot of time with the military, often wearing his military attire and dining and sleeping alongside his soldiers. He is perhaps most famous for building Hadrian's Wall, the wall that marked the northern limit of Britannia.

Hadrian was a philhellene (admirer of Greek culture) in most of his tastes as well as a humanist, and is regarded among the 'Five Good Emperors'. He adopted Lucius Aelius as his heir in 136, but the latter died two years later in January 138. He eventually adopted Antoninus Pius as his successor, so long as Antoninus agreed to adopt Marcus Aurelius and Lucius Verus, Lucius Aelius' son, as his heirs. Hadrian died of heart failure on the 10th of July, 138.