| Theme of Opsikion Ὀψίκιον, θέμα Ὀψικίου | |
|---|---|
| Theme of the Byzantine Empire | |
| 640s/660s–1230s | |
 The Asian themes of the Byzantine Empire c. 780 | |
| Capital | Ancyra, then Nicaea |
| Historical era | Middle Ages |
• Established | 640s/660s |
• Fall to the Latins | 1234 |
| Today part of | Turkey |
The Opsician Theme (Greek: θέμα Ὀψικίου, thema Opsikiou) or simply Opsikion (Greek: [θέμα] Ὀψίκιον, from Latin: Obsequium) was a Byzantine theme (a military-civilian province) located in northwestern Asia Minor (modern Turkey). Created from the imperial retinue army, the Opsikion was the largest and most prestigious of the early themes, being located closest to Constantinople. Involved in several revolts in the 8th century, it was split in three after ca. 750, and lost its former pre-eminence. It survived as a middle-tier theme until after the Fourth Crusade.