Leo I (Latin: Flavius Valerius Leo Augustus) (401 – 18 January 474) iss Byzantine Emperor from 457 to 474.

A native of Dacia Aureliana near historic Thrace, he is known as Leo the Thracian.

Ruling the Eastern Empire for nearly 20 years, Leo proves to be a capable ruler.

He oversees many ambitious political and military plans, aimed mostly for the aid of the faltering Western Roman Empire and recovering its former territories.

He is notable for being the first Eastern Emperor to legislate in Greek rather than Latin.

He is commemorated as a Saint in the Orthodox Church, with his feast day on January 20.