Zeno (; Greek: Zenon; c. 425 9 April 491) was Eastern Roman emperor from 474 to 475 and again from 476 to 491. Domestic revolts and religious dissension plagued his reign, which nevertheless succeeded to some extent in foreign issues. His reign saw the end of the Western Roman Empire following the deposition of Romulus Augustus and the death of Julius Nepos, but he was credited with contributing much to stabilising the Eastern Empire.

In ecclesiastical history, Zeno is associated with the Henotikon or "instrument of union", promulgated by him and signed by all the Eastern bishops, with the design of solving the monophysite controversy. The Henotikon was widely unpopular and eventually abandoned under Justin I.

Leo II (Greek: Λέων, Leōn; c. 467 – November 474) was briefly Roman emperor in 474 when he was a child aged six or seven. He was the son of Zeno, the Isaurian general and future emperor, and Ariadne, a daughter of the emperor Leo I (r. 457–474), who ruled the eastern Roman empire. Leo II was made co-emperor with his grandfather Leo I on 17 November 473, and became sole emperor on 18 January 474 after Leo I died of dysentery. His father Zeno was made co-emperor by the Byzantine Senate on 29 January and they co-ruled for a short time before Leo II died in November 474. The precise date of Leo's death is unknown.