Church is a blue Persian cat that lives in the New York Institute with the Lightwoods. He acts as a guide and always knows where in the Institute everyone is. He has a soft spot for fish and feels uncomfortable when the Silent Brothers are around.
Church seems to understand human language, as he can follow instructions from anyone who needs information. He is usually fond of people he recognizes. He does, however, hate Luke because of his werewolf origin.
In Clockwork Angel, it is revealed that he was meant to be a sacrifice by Mrs. Dark in her attempt to resurrect her sister, Mrs. Black, but was rescued by Jem Carstairs. He was first called "the church cat" which quickly became simply "Church."
In Clockwork Princess it is revealed that Church traveled from London to New York in 1878 as Magnus Banes companion. It is unknown how Church came to live in the New York institute with the Lightwoods instead of staying with Magnus.