John P. Volz, Sr. (April 22, 1935 – February 12, 2011) was a prominent lawyer from New Orleans, Louisiana. He was the attorney for the United States District Court for the Eastern District of Louisiana under President Jimmy Carter, a Democrat, and Presidents Ronald W. Reagan and George Herbert Walker Bush, both Republicans. Volz in time prosecuted reputed Mafia figure Carlos Marcello, Louisiana commissioner of administration Charles E. Roemer, II, Orleans Parish District Attorney Harry Connick Sr., Louisiana State Senate President Michael H. O'Keefe, Sr., and Governor Edwin Washington Edwards.