Irwin Thornton Catharine (October 22, 1883 – March 3, 1944) was the chief architect of Philadelphia public schools from 1920 until his retirement in 1937. Buildings built during Catharine's tenure ranged from Gothic Revival, as in the case of Simon Gratz High School, to Streamline Moderne, as in his last project, Joseph H. Brown Elementary School. He died in Philadelphia in 1944. A number of his works are listed on the U.S. National Register of Historic Places. Works (all in Philadelphia) include: If Catharine has notable works outside of Philadelphia, none are listed on the National Register.