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| Theodore I Palaiologos | |
|---|---|
 Fresco from the Church of the Virgin Hodegetria in Mystras representing the despot Theodore I as ruler and monk. | |
| Despot of the Morea | |
| Reign | 1383–1407 |
| Predecessor | Demetrios I Kantakouzenos |
| Successor | Theodore II Palaiologos |
| Born | c. 1355 |
| Died | 24 June 1407 (aged c. 52) |
| Spouse | Bartolomea Acciaioli |
| Dynasty | Palaiologos |
| Father | John V Palaiologos |
| Mother | Helena Kantakouzene |
| Religion | Greek Orthodox |
Theodore I Palaiologos (or Palaeologus) (Greek: Θεόδωρος Α΄ Παλαιολόγος, romanized: Theodōros I Palaiologos) (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.