Byzantine Senate in the context of "Theodosius III"

The Roman Senate (Latin: Senātus Rōmānus) was the highest and constituting assembly of ancient Rome and its aristocracy. With different powers throughout its existence, it lasted from the first days of the city of Rome (traditionally founded in 753 BC) as the Senate of the Roman Kingdom, to the Senate of the Roman Republic and Senate of the Roman Empire and eventually the Byzantine Senate of the Eastern Roman Empire, existing well into the post-classical era and Middle Ages.

During the days of the Roman Kingdom, the Senate was generally little more than an advisory council to the king. However, as Rome was an electoral monarchy, the Senate also elected new Roman kings. The last king of Rome, Lucius Tarquinius Superbus, was overthrown following a coup d'état led by Lucius Junius Brutus, who founded the Roman Republic. During the early Republic, the Senate was politically weak, while the various executive Roman magistrates who appointed the senators for life (or until expulsion by Roman censors) were quite powerful. Since the transition from monarchy to constitutional rule was most likely gradual, it took several generations before the Senate was able to assert itself over the executive magistrates. By the middle Republic, the Senate had reached the apex of its republican power. The late Republic saw a decline in the Senate's power, which began following the reforms of the tribunes Tiberius and Gaius Gracchus. After the transition of the Republic into the Principate, the Senate lost much of its political power as well as its prestige.

Leo II (Ancient Greek: Λέων, Leōn; c. 467 – 474), called the Younger, briefly reigned as a child emperor of the Eastern Roman Empire from 473 to 474. He was the son of Zeno, the Isaurian general and future emperor, and Ariadne, a daughter of the emperor Leo I (r. 457–474). 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 late 474. He is sometimes surnamed with the epithet "the Small" (Latin: Minor; Ancient Greek: ὁ Μικρός), probably to distinguish him from his grandfather and augustus Leo I (Ancient Greek: ὁ Μέγας, romanized: ho Mégas, lit. 'the Great').

Nikephoros III Botaneiates (Greek: Νικηφόρος Βοτανειάτης, romanized: Nikēphóros Botaneiatēs; 1002–1081), Latinized as Nicephorus III Botaniates, was Byzantine Emperor from 7 January 1078 to 1 April 1081. He became a general during the reign of Byzantine Emperor Constantine IX Monomachos, serving with distinction during the Pecheneg revolt of 1048–1053. In 1057 he aided Isaac I Komnenos in overthrowing Emperor Michael VI Bringas, leading forces at the decisive Battle of Petroe. Under the Emperor Constantine X Doukas Nikephoros was made doux, first of Thessalonica and subsequently of Antioch. In the latter position he repelled numerous incursions from the Emirate of Aleppo. Constantine X died in 1067 and Empress Eudokia Makrembolitissa married Romanos IV Diogenes; Nikephoros, who had also been a candidate for Eudokia's hand and the position of emperor, was exiled and remained in retirement until Emperor Michael VII summoned him to serve as kouropalates and governor of the Anatolic Theme.

Having insulted Emperor Michael with overly frank appeals for help against the Seljuk Turks in Byzantine Anatolia, Nikephoros decided to protect himself from reprisals by seizing the throne. His military acumen and family renown won him strong support, and he took power in 1078 with the approval of the Byzantine Senate and the citizens of Constantinople. As emperor he faced numerous revolts, including those of Nikephoros Bryennios, Nikephoros Basilakes, and Constantine Doukas, as well as an attempted assassination by the Varangian Guard. Nikephoros performed many acts to increase his legitimacy and support, spending large amounts on donatives for the army and his supporters, forgiving all debt in arrears, and instituting minor legal reforms. Diplomatically, he secured the submission of Theodore Gabras and Philaretos Brachamios, governors of Trebizond and Antioch, respectively, who had become de facto independent of the Byzantine Empire.