Leo I, also known as "the Thracian", was Roman emperor of the East from 457 to 474. He was a native of Dacia Aureliana near historic Thrace. He is sometimes surnamed with the epithet "the Great", probably to distinguish him from his young grandson and co-augustus Leo II.

Procopius Anthemius was the Western Roman emperor from 467 to 472. Born in the Eastern Roman Empire, Anthemius quickly worked his way up the ranks. He married into the Theodosian dynasty through Marcia Euphemia, daughter of Eastern emperor Marcian. He soon received a significant number of promotions to various posts, and was presumed to be Marcian's planned successor. However, Marcian's sudden death in 457, together with that of Western emperor Avitus, left the imperial succession in the hands of Aspar, who instead appointed Leo, a low-ranking officer, to the Eastern throne, probably out of fear that Anthemius would be too independent. Eventually, this same Leo designated Anthemius as Western emperor in 467, following a two-year interregnum that started in November 465.