Today the Church commemorates St. Gennadios, the Patriarch of Constantinople. Sources often mistakenly mix up St. Gennadios, Patriarch of Constantinople in the fifth century, with this blog’s Patron Patriarch, Gennadios Scholarios, who was Patriarch of Constantinople a millennium later. Because of this we sometimes see people calling Gennadios Scholarios a saint when he isn’t (although in the Prologue of Ohrid, St. Nikolai Velimirović calls him “the glorious Patriarch” on the feast day for St. Mark of Ephesus).
St. Gennadios was Patriarch from 458 to his death in 471. He may have been friends with St. Cyril of Alexandria earlier, and during his patriarchate he definitely corresponded with Pope St. Leo of Rome. As one can imagine, he was a defender of Chalcedon and he also presided a council against simony (he cared about the purity of his clergy: it is said he would only ordain those who knew the entire Psalter by heart). Aside from ecclesiastical affairs, he was known as a miracle-worker and was a man of learning who wrote scriptural commentaries, some fragments of which may be found in Patrologia Graeca, 85 along with some of his other writings.
UPDATE, 10/10/2016: Turns out that Gennadios Scholarios is commemorated as a saint on some calendars, see here.