John Roderick MacArthur (December 21, 1920 – December 15, 1984) was a U.S. businessman and philanthropist. The J. Roderick MacArthur Foundation, a philanthropic organization interested in civil liberties in the United States, and the MacArthur Justice Center at the Northwestern University School of Law are named after him. He is the son of John D. MacArthur who established the John D. and Catherine T. MacArthur Foundation.