Athanasius I of Constantinople

Athanasius I (Ἀθανάσιος; 1230 – 28 October 1310) was the Ecumenical Patriarch of Constantinople for two terms, from 1289 to 1293 and 1303 to 1309. He was born in Adrianople and died in Constantinople. Chosen by the emperor Andronicus II Palaeologus as patriarch, he opposed the reunion of the Greek and Roman Churches and introduced an ecclesiastic reform that evoked opposition within the clergy. He resigned in 1293 and was restored in 1303 with popular support. The pro-Union clerical faction forced him into retirement in early 1310.

He is commemorated as a saint in the Orthodox Church with his feast day observed annually on 28 October.