Theodore I Palaiologos (or Palaeologus) () (c. 1355 – 24 June 1407) was despot (despotēs) in the Morea from 1383 until his death on 24 June 1407. A son of Emperor John V Palaiologos, Theodore was the first member of the Palaiologos dynasty appointed as the Despot of the Morea, following the final defeat of the rival Kantakouzenos clan, who under John VI Kantakouzenos had attempted to usurp rule of the Byzantine Empire. Theodore conducted several military campaigns to expand his province, successfully annexing several Latin possessions that remained there since the aftermath of the Fourth Crusade. He died without known heirs and was succeeded as Despot of the Morea by Theodore II, a son of Emperor Manuel II Palaiologos. Biography Theodore was the youngest surviving son of the Byzantine Emperor John V Palaiologos and his wife Helena Kantakouzene. His maternal grandfather was former Emperor John VI Kantakouzenos. His older brothers were Emperor Andronikos IV Palaiologos and Manuel II Palaiologos. In 1376 Theodore I Palaiologos, already named despotēs, was charged with governing Thessalonica by his father John V, but before he could take possession of the city, he was arrested and imprisoned together with his father and his brother Manuel by his eldest brother Andronikos IV. This captivity in the Prison of Anemas in Constantinople lasted throughout Andronikos' usurpation, from 1376 until 1379. Soon after the restoration of John V, Manuel was appointed to rule in Thessalonica, and Theodore was eventually transferred to Morea. The Morea had remained in the hands of Manuel Kantakouzenos, a younger son of Emperor John VI, even after the latter's abdication in 1354. Manuel died in 1380 and was succeeded by his older brother, the former co-emperor Matthew Kantakouzenos, who died or retired in 1383. By this time Theodore was appointed to rule the Morea (in 1382), but Matthew was briefly succeeded by his son perhaps Demetrios I Kantakouzenos. Theodore I Palaiologos arrived in the Morea in 1383 and successfully took possession of the province. The young despotēs soon commenced wars for the expansion of his province. His military campaigns were arguably the most successful Byzantine military operations since the annexation of large regions of Thessaly and Epirus by his paternal grandfather Andronikos III Palaiologos earlier in the 14th century. In order to increase the potential manpower of his army, Theodore encouraged the settlement of Albanians in Morea, and recruited them as troops against local