Basiliscus (Ancient Greek: Βασιλίσκος, romanized: BasilÃskos; died 476/477) was Eastern Roman emperor from 9 January 475 to August 476. He became magister militum per Thracias in 464, under his brother-in-law, Emperor Leo I (r. 457–474). Basiliscus commanded the army for an invasion of the Vandal Kingdom in 468, which was defeated at the Battle of Cape Bon. There were accusations at the time that Basiliscus was bribed by Aspar, the magister militum; many historians dismiss this, instead concluding that Basiliscus was either incompetent or foolish for accepting Vandal King Gaiseric's offer of a truce, which the latter used to construct fireships. Basiliscus's defeat cost the Eastern Empire 130,000 pounds (59,000 kg) of gold, causing the empire to hover above bankruptcy for 30 years. When Basiliscus returned to Constantinople, he sought refuge in the Hagia Sophia. His sister, Empress Verina, secured him a pardon and he left the church to retire in Neapolis.
When Emperor Leo died in 474, his grandson Leo II (r. 474) took power, but soon died; his father, Zeno (r. 474–475, 476–491) ascended the throne in the same year, in a politically precarious position. Verina conspired to install the magister officiorum Patricius, her lover, as emperor. This plot was supported by Basiliscus, who succeeded in recruiting Isaurian brothers Illus and Trocundes, as well as Verina's nephew Armatus. Zeno fled on 9 January 475, either after learning of the plot or after Verina warned him that his life was in danger. Although Patricius was Verina's intended successor, Basiliscus convinced the Eastern Roman Senate to acclaim him instead.