St. Basil is most well known for defending the doctrines of the trinity and the incarnation against heresies of the day. Yet the biggest heresy he had to defend was the divinity of Christ. These are fundamental beliefs of the Church, and we owe St. Basil thanks for seeing to it that the mission of the Church–to defend the deposit of faith created by Christ–was lived out.
Yet St. Basil was also the model bishop. He was known to visit every church in the diocese several times throughout the year. He also started hospitals and shelters, and, as a result, is the patron saint of hospital reformers.
During the time he was archbishop, there was a great division among Catholics in the east and the west, rooted in misunderstandings. Both sides saw wrong in the other and neither trusted the other side. Yet St. Basil worked for peace when others had long given up on it. Not surprisingly, he was misunderstood. It seemed that his efforts towards unity were fruitless. He died at 49 on January 1st.
He is also known as the Father of Eastern Monasticism.