For 10 points, name this Byzantine ruler who built the Hagia Sophia.
This man employed such officials as the poet Paul the Silentiary, and a notable account of his reign was written by Agathias. He ended the Lazic War by dispatching his envoy Peter the Patrician, and during his reign, Totila was slain at the Battle of Taginae. This man ordered the officer Mundus to attack the supporters of Anastasius' nephew, (*) Hypatius. This monarch, a supporter of the "Blues" faction of chariot racing enthusiasts, employed such scholars as Tribonian, who helped to compile the legislative collection Corpus juris civilis. This husband of Theodora was the target of the Nika riots and the ruler who dispatched his general Belisarius to retake Western Roman lands. For 10 points, name this Byzantine ruler who built the Hagia Sophia.
This man employed such officials as the poet Paul the Silentiary, and a notable account of his reign was written by Agathias.
Justinian I [or Justinian the Great; prompt on "Justinian"]