One of the saints under the Anastasis (see earlier).

I was informed this is St. Gregory the Theologian, aka Gregory of Nazianzus, 4th c. From the Wikipedia: Gregory of Nazianzus (329 – January 25, 389), also known as Gregory the Theologian or Gregory Nazianzen, was a 4th-century Archbishop of Constantinople. He is widely considered the most accomplished rhetorical stylist of the patristic age. As a classically trained speaker and philosopher he infused Hellenism into the early church, establishing the paradigm of Byzantine theologians and church officials.