Leo I: emperor of the East-Roman (Byzantine) empire (457-474).
- c.401: full name unknown
- 7 February 457: recognized as emperor
- 18 January 474: natural death
nicknamed "the great Thracian" and "the Butcher"
Successor of: Marcianus
- 457 Marcian dies without successor; general Aspar appoints Leo; he is crowned by patriarch Anatolius
- in the Sasanian Empire, Yazdgard II is succeeded by Hormizd III (died 459) and Peroz; during Leo's reign, Ricimer is military leader in the west
- 458 Consul with Majorian (in the west), who is recognized as emperor by Ricimer and Leo I
- 461 Ricimer replaces Maiorianus as emperor in the west by Libius Severus
- 462 Consul II (with Libius Severus)
- 465 Ricimer puts Libius Severus to death
- 466 Consul III (with Tatianus)
- 467 Leo's daughter Ariadne marries Zeno; Ricimer and Leo make Anthemius emperor in the west
- 468 Anthemius consul II (without colleague); the Huns defeated; Leo's expedition against king Gaiseric of the Vandals fails; at the same time, Anthemius' expedition against the Visigoths ends in disaster
- 469 Zeno consul (with Flavius Marcianus); Aspar tries to kill Leo, and very nearly succeeds
- 471 Consul IV (with Caelius Aconius Probianus); Aspar's son Ardabur conspires against Leo; Leo orders the execution of Aspar and Ardabur
- 472 Ricimer captures Rome, kills Anthemius, appoints Olybrius; Leo refuses to recognize the new emperor, who dies of dropsy in the same year, two months after Ricimer
- 473 Consul V (without colleague); Ricimer is succeeded as military leader in the west by his son Gundobad, who appoints Glycerius emperor in the west; Leo appoints his grandson Leo II as successor; this creates tensions his son-in-law Zeno
- 474 Leo II consul; Leo ignores the new ruler in the west and sends Julius Nepos to Italy; death of Leo I.
- Leo II dies soon after. Zeno has great difficulty to establish his reign and has to leave Constantinople in 475. During this crisis, the West-Roman empire disintegrates
Buildings: Church of St. John of the Stadium
Succeeded by: Leo II, Zeno I
- 459 Death of Simeon Stylites