This is the first of three Church history Minutes on the Cappadocian Fathers, this week “Basil the Great” (aka Basil of Caesarea)
Who was he? An early Christian bishop who, together with Gregory of Nyssa (his little brother) and Gregory Nazianzus, made up the Cappadocian fathers, a set of early defenders of Nicene Christianity. Nicene Christianity predominantly defended the full deity of Christ (as God, not just a creation of God) against the Arians. Eventually it would also come to represent Trinitarian Faith. While it remained in part due to Athanasius, it developed and lasted, largely, due to the efforts of the Cappadocian fathers. Since they existed prior to the East/West split, almost all Christians can consider them as part of their heritage.
Why was he important? The Trinitarian faith you have now was systematized by the Cappadocians. This is not to say that it is not biblical, but the arguments for it from the bible (and elsewhere) were first made by these men. Basil was known more for his political savvy, but he did write an important defense of the Holy Spirit as the third member of the Trinity (that is equally God). Many of the debates directly with Arians were done by Basil.
Fun Fact: When a rival defender of Arianism was sent to Basil to debate the issue by the, then Arian, emperor, Basil was so firmly against Arianism that the emissary from the emporer remarked on how he had never been spoken to in such a manner. Basil replied “then you must not have spoken to a Bishop before.” The emissary was enraged and suggested war, but the emperor declined.
Where might I have heard of him? Outside of being a Cappadocian Father, he is also one of the key figures in establishing communal monasticism (as opposed to the then dominate dessert monasticism that was done in isolation).