Olympianus ( el, Ὀλυμπιανός, died 198) was the

bishop of Byzantium The ecumenical patriarch ( el, Οἰκουμενικός Πατριάρχης, translit=Oikoumenikós Patriárchēs) is the archbishop of Constantinople (Istanbul), New Rome and ''primus inter pares'' (first among equals) among the heads of the ...

for eleven years (187–198 AD). He succeeded Bishop Pertinax. In 196 Byzantium was conquered by Emperor

Septimius Severus Lucius Septimius Severus (; 11 April 145 – 4 February 211) was Roman emperor from 193 to 211. He was born in Leptis Magna (present-day Al-Khums, Libya) in the Roman province of Africa. As a young man he advanced through the customary suc ...

during his rivalry with Pescennius Niger. Septimius Severus took the right of metropolis from the city and made it part of the Heracleia. Byzantium remained a bishopric under Heracleia for more than a century. Olympianus' successor was Marcus I.

Sources

www.ec-patr.org
2nd-century Romans 2nd-century Byzantine bishops 198 deaths Bishops of Byzantium Year of birth unknown {{EarlyChurch-bishop-stub