Rowan LeCompte designed the dramatic clerestory windows, which are some of the most notable in the building. Check out the first link for a good story about him and his greatest design challenge.
Lawrence Saint was the original stained glass master of the cathedral; he created the actual formulas for the different colors of glass that are used in the building, and oversaw the creation of many of the early windows.
More recently Brenda Belfield has done a lot of the newest windows, more than 60 of them.
Two major contributors to the stained-glass windows of the Washington National Cathedral are Lawrence Bradford Saint and Rowan LeCompte. Saint in noted for early work within the Cathedral and LeCompte for his design and creation of over 45 windows within the Cathedral.
Lawrence Bradford Saint (1885-1961) was an American stained glass artist. At the height of his career he produced many windows for the National Cathedral. He also served as head of the stained glass department. Saint created the three parable windows in St. Mary’s chapel north of the choir which depicted seven of Christ’s parables. He also created the large rose window in the northern transept, the Foretellers of Judgment windows below it
Rowan LeCompte was inspired by the works of Saint when he visited the National Cathedral when he was 13. LeCompte went on to design and install more than 45 windows for the Cathedral. His most popular work is the Creation Rose window set above the west front portal in 1976. LeCompte’s first commissioned work for the National Cathedral was undertaken when he was only 16 years old.