| John Doukas Ιωάννης Δούκας | |
|---|---|
| Usurper of the Byzantine Empire | |
| Reign | 1074 |
| Predecessor | Michael VII |
| Successor | Nikephoros III |
| Born | ? |
| Died | c. 1088 |
| Spouse | Irene Pegonitissa |
| Issue | Andronikos Doukas Constantine Doukas |
| Dynasty | Doukas |
| Father | Andronikos Doukas |
John Doukas (or Ducas) (Greek: Ιωάννης Δούκας, Iōannēs Doukas) (died c. 1088) was the son of Andronikos Doukas, a Paphlagonian Greek nobleman who may have served as governor of the theme of Bulgaria (Moesia), and the younger brother of Emperor Constantine X Doukas. John Doukas was the paternal grandfather of Irene Doukaina, wife of Emperor Alexios I Komnenos.
He was the original owner of Codex Parisinus graecus 2009, i.e. the oldest known and preserved manuscript of De administrando imperio of Emperor Constantine VII Porphyrogenitus copied by one of Doukas' scribes, a well-known encyclopedic Byzantine source on foreign nations from the 10th century.[1]