Theophylact or Theophylaktos was the eldest son of the Byzantine emperor Michael I Rangabe and grandson, on his mother's side, of Nikephoros I. He was junior co-emperor alongside his father for the duration of the latter's reign, and was tonsured, castrated, and exiled to Plate Island after his overthrow, under the monastic name Eustratius.
- Occupation
- monk, eunuch
- Position held
- Byzantine emperor
- Citizenship
- Byzantine Empire
- Born
- 793, 792
- Died
- January 15, 849, January 15, 849
