Father Thomas Higgins is the priest of Saint Michael's Catholic Church in Duston Heights, Massachusetts where Johnny Dixon and his grandparents attend, and has an extensive knowledge of Catholic rites that have proven useful on various occasions in exorcising spirits and other demonic entities.
Higgins is a World War II veteran who was wounded in a battle on the island of Guam. He becomes the priest of Johnny’s school and church (The Curse of the Blue Figurine) and, while Johnny interacts with the priest, it’s not until Professor Childermass’s disappearance that the two become close (The Spell of the Sorcerer's Skull).
The local diocese relocates Higgins from Duston Heights to nearby Rocks Village. After his transfer the spirit of a long dead De Marisco knight take possession of the priest and leads him on a strange mission across England (The Secret of the Underground Room).
Bellairs grew up in the Catholic Church and the background of Catholicism runs deeply throughout nearly all of his writings, starting with Saint Fidgeta. Father Higgins plays a rather unique role in that he is the only regular character in all of Bellairs' young-adult fiction to be closely connected to the church, giving the Dixon series slightly more religious overtones.