William M. "Bill" Napoli (born June 17, 1948) is a former Republican state senator in the South Dakota State Legislature, representing the 35th State Senate district. He retired in 2008. On March 20, 2008, Napoli announced that he would not seek re-election and instead would retire from politics. In the Rapid City Journal, Napoli stated that he would run for governor "if his supporters ask him to".