O'Dea High School is a Catholic all boys high school founded in 1923 and is located in Seattle's First Hill neighborhood. The school is named after Edward John O'Dea who was bishop of Seattle when the school was built. O'Dea is a part of the Archdiocese of Seattle.

The Archdiocese of Seattle is a Latin Church ecclesiastical territory, or archdiocese, of the Catholic Church in western Washington State in the United States. The Diocese was known as the Diocese of Nesqually from 1850 to 1907. The mother church of the archdiocese is St. James Cathedral in Seattle. The former cathedral is the Proto-Cathedral of St. James the Greater in Vancouver. Its archbishop since 2019 is Paul D. Etienne.