Msgr Seamus Brennan was born and raised in Ireland.  He graduated from Saint John's College of Waterford, Ireland and was ordained a priest for the diocese of Trenton on June 4, 1972.  Priestly assignments have included associate pastor at Saint Barnabas of Bayville and Saint Philip and James of Phillipsburg.  He served as pastor of Saint John's of Lambertville, Saint Matthews of Edison, and Immaculate Conception of Somerville.  When ministering at Phillipsburg, Msgr. Brennan worked in both Saint Philip and James elementary school and Phillipsburg Catholic High School for 8 years.  As pastor in Edison, he served as Director of Saint Matthew’s school for over 17 years and while pastor in Somerville, he served as Director of Immaculate Conception elementary and Immaculata High School for almost 18 years.

On a diocesan level he has served as Vicar for priests personnel , Episcopal Vicar and Dean. Currently he serves on the Presbyteral Council and as a member of the Board of Consultors.  Msgr Brennan lives in retirement at Saint James Church of Basking Ridge and assists in ministry there and at numerous parishes throughout the diocese.