Leo II (emperor) in the context of "Basiliscus"

The Leonid dynasty or Thracian dynasty produced six Byzantine emperors during Late Antiquity, reigning over the Byzantine Empire from 457 to 518. The dynasty's patriarch was Leo I, who was made Byzantine emperor in 457. Leo's daughter Ariadne became empress and mother to an emperor, and her two husbands were themselves each made emperor in turn. Another relative whose name does not survive of Leo I or his wife Verina married the future augustus Julius Nepos (r. 474–480), the last emperor in the Western Roman Empire. The dynasty of Leo succeeded the preceding Valentinianic dynasty (r. 364–455) and Theodosian dynasty (r. 379–457) whose family trees were conjoined and ruled concurrently. Besides Julius Nepos, who administered no more than a rump state the Roman province of Dalmatia in the western empire during the fall of the west, the dynasty's emperors governed the Byzantine Empire (east).

Leo's eldest daughter Ariadne married Zeno, and their son, Leo II was proclaimed augustus and succeeded his grandfather Leo as an infant, appointing Zeno co-augustus. Leo's younger daughter, Leontia, married first the caesar Patricius, son of the magister militum Aspar, and then Marcianus, son of the augustus Anthemius (r. 467–472). When Leo II died in the year of his grandfather's death, Zeno remained augustus in the Byzantine Empire.

Zeno (/ˈziːnoʊ/; Ancient Greek: Ζήνων, romanized: Zénōn; c. 425 – 9 April 491) was Eastern Roman emperor from 474 to 475 and again from 476 to 491. His reign was plagued by domestic revolts and religious dissension, but was more successful on the foreign front. He is credited with further stabilizing the Eastern empire, while the Western Roman Empire fell following the deposition of Romulus Augustulus.

Born in Isauria, Zeno was known as Tarasis before adopting his Greek name and becoming an ally of Emperor Leo I, who saw the Isaurian general as an important counterweight against the Germanic leader Aspar. In 466, he married Leo I's daughter, Ariadne, with whom he had a son, Leo. On the death of Leo I in 474, Zeno's seven-year-old son took the throne as Leo II, with Zeno made co-emperor shortly after. Leo II died of an illness later that year, leaving Zeno as the sole emperor.

Leo I (Ancient Greek: Λέων, romanized: Leōn; c. 401 – 18 January 474), also known as the Thracian (Latin: Thrax; Ancient Greek: ὁ Θρᾷξ), was Eastern Roman emperor from 457 to 474. He was a native of Dacia Aureliana near historic Thrace. He is sometimes surnamed with the epithet the Great (Latin: Magnus; Ancient Greek: ὁ Μέγας), probably to distinguish him from his young grandson and co-augustus Leo II (Ancient Greek: ὁ Μικρός, romanized: ho Mikrós, lit. 'the Small').

During his 17-year rule, he oversaw a number of ambitious political and military plans, aimed mostly at aiding the faltering Western Roman Empire and recovering its former territories. He is notable for being the first Eastern Emperor to legislate in Koine Greek rather than Late Latin. He is commemorated as a saint in the Eastern Orthodox Church, with his feast day on 20 January.

Aelia Verina (Greek: Βερίνα; died 484) was the Eastern Roman empress as the wife of Leo I. She was a sister of Emperor Basiliscus. Her daughter Ariadne also became empress. Verina was the maternal grandmother of Leo II.