Short answers, pulled from the story.
Justinian I, also known as Justinian the Great, was Roman emperor from 527 to 565. Born in 482 in Tauresium in Dardania, he came from a peasant family and was adopted by his uncle Justin, who brought him to Constantinople.
The Corpus juris civilis was the complete revision of all Roman law overseen by the quaestor Tribonian under Justinian I. It consists of the Codex Justinianeus, the Digesta, the Institutiones, and the Novellae, and it became the basis of much Continental European law after reaching Western Europe in the 12th century.
The Nika riots were an uprising in January 532 in which the chariot racing factions of Constantinople united against Justinian I and tried to replace him with the senator Hypatius. Justinian's generals Belisarius and Mundus suppressed the revolt, and Procopius records that 30,000 unarmed civilians were killed in the Hippodrome.
Justinian I recovered large parts of the western Mediterranean, including the Vandal Kingdom in North Africa, the Ostrogothic Kingdom in Italy, and the south of the Iberian Peninsula as the province of Spania. His general Belisarius captured Carthage and Rome, and Narses won a decisive victory at Busta Gallorum where the Ostrogothic king Totila was slain.
Theodora was the wife of Justinian I, whom he married around 525 in Constantinople. She had been an actress by profession and was some twenty years his junior, and she became very influential in imperial politics, including refusing to flee during the Nika riots. She died in 548, possibly of cancer.
Justinian I rebuilt the Hagia Sophia after the Nika riots under the architects Isidore of Miletus and Anthemius of Tralles, at a cost of 20,000 pounds of gold. His building program also included the Church of Saints Sergius and Bacchus, the San Vitale in Ravenna, underground cisterns for Constantinople, an arch dam at Dara, and the Sangarius Bridge in Bithynia.
Justinian I died in his sleep on the night of the 14th of November 565, childless. He was succeeded by his nephew Justin II and was laid to rest in a golden tomb in the Church of the Holy Apostles, which was desecrated and robbed during the pillage of the city in 1204 by the Latin States of the Fourth Crusade.