Richard’s son William was born in 1163. William was twice married. By his first wife, he had two sons, Richard and Walter; both were men of note in their day, and extended the territory and influence of the family. William married, as his second wife, Marjory Countess of Buchan, only daughter of Earl Fergus—mentioned before; and thus Comyn became Earl of Buchan. So he was the common ancestor of the Lords of Badenoch and the Earls of Buchan— of the Comyn line. He was appointed Justiciary of Scotland. In 1222 Alexander II. appointed him guardian of the Earldom of Moray. He founded the Cistercian Abbey of Deer, which was dedicated to St. Mary. Earl William died in 1233, and was succeeded by his son, Alexander, second Earl of Buchan of the name of Comyn.

References: [AR7],[MCS5],[PRES.GED]