1346), usually simply Theodore Synadenos, was a Byzantine magnate, senior official and military leader of the early 14th century, who played an important role in the civil wars of the period.

[2][3] Little is known about his early life: he was born circa 1277, apparently at Bizye on the Black Sea coast of Thrace, where he had a palatial residence, extensive estates and many friends and relatives.

Along with the fellow aristocrats John Kantakouzenos and Syrgiannes Palaiologos, Theodore formed the leading "triumvirate" of the younger Andronikos's supporters, to which the "new man" Alexios Apokaukos attached himself as a junior member.

[5] In the first round of the civil war between grandfather and grandson, Andronikos III was successful in getting recognition for himself as junior emperor, with Thrace as his personal appanage.

The common people, impoverished by an exploitative and over-powerful aristocracy, viewed Kantakouzenos as a representative of the hated aristocrats and rallied behind the legitimate Palaiologos line and one by one, the cities were seized in the name of the Constantinopolitan regency.

Such a move might well prove decisive, as possession of Thessalonica would enable Kantakouzenos to control Macedonia, Thessaly and Epirus, and in March 1342, he set out from Didymoteichon with his army in the direction of the city.

[21][23] Driven from Thessalonica, with Kantakouzenos's cause seemingly in ruins—he was soon forced to seek refuge in the court of the Serbian king, Stefan Dushan—and with his family back in Constantinople in the regency's hands, Synadenos made terms with Apokaukos.

[1][4][25] A year later, in February 1347, Kantakouzenos entered Constantinople as the victor of the civil war,[26][27] which had left the Byzantine state in ruins: its human and military resources exhausted, over half of its territory lost, bankrupt and indebted to foreigners, with a war-weary and unenthusiastic populace.