Roman emperor
The Western Roman Empire collapsed in the late 5th century. Romulus Augustulus is often considered to be the last emperor of the West after his forced abdication in 476, although Julius Nepos maintained a claim recognized by the Eastern Empire to the title until his death in 480. Following Nepos' death, the Eastern Emperor Zeno abolished the division of the position and proclaimed himself as the sole Emperor of a reunited Roman Empire. The Eastern imperial lineage continued to rule from Constantinople ("New Rome"); they continued to style themselves as Emperor of the Romans (later βασιλεύς Ῥωμαίων in Greek), but are often referred to in modern scholarship as Byzantine emperors. Constantine XI Palaiologos was the last Roman emperor in Constantinople, dying in the Fall of Constantinople to the Ottomans in 1453.
Theodosian dynasty
Its founding father was Flavius Theodosius (often referred to as Count Theodosius), a great general who had saved Britannia from the Great Conspiracy. His son, Flavius Theodosius was made emperor of the Eastern Roman Empire in 379, and briefly reunited the Roman Empire 394–395 by defeating the usurper Eugenius. Theodosius I was succeeded by his sons Honorius in the West and Arcadius in the East. The House of Theodosius was related to the Valentinian Dynasty by marriage, since Theodosius I had married Galla, a daughter of Valentinian I. Their daughter was Galla Placidia. The last emperor in the West belonging to the dynasty was Galla Placidia's son Valentinian III. The last emperor of the dynasty in the East was Theodosius II, the son of Arcadius. Later, both in the East and in the West, the dynasty briefly continued, but only through marriages: Marcian became emperor by marrying Pulcheria, the older sister of Theodosius II, after the death of the latter, Petronius Maximus was married to Licinia Eudoxia, the daughter of Theodosius II, and Olybrius was married to Placidia, the daughter of Valentinian III. Anthemius is also sometimes counted to the dynasty as he became a son-in-law of Marcian. Descendants of the dynasty continued to be part of the East Roman nobility at Constantinople until the end of the 6th century.In "italics" the Augusti and the Augustae.