William Fitzgerald may refer to:

• William Fitzgerald (bishop)
• William Fitzgerald, American politician
• William FitzGerald-de Ros, 23rd Baron de Ros (1797-1874), British Lord and General officer
• William Charles Fitzgerald (1938-1967), a United States Navy officer who was killed in action during the Vietnam War
• William F. Fitzgerald (1846-1903), California Attorney General and a California Supreme Court justice
• William J. Fitzgerald (1887-1947), U.S. Representative from Connecticut
• Sir William Robert Seymour Vesey-FitzGerald KCSI GCSI PC (1818-1885), British politician
• William S. Fitzgerald (1880?1937), American politician
• William Vesey-FitzGerald, 2nd Baron FitzGerald and Vesey and 1st Baron FitzGerald, PC (1783-1843), Irish statesman
• William T. Fitzgerald (1858-1939), U.S. Representative from Ohio
• William Robert Fitzgerald Collis (1900 ? 1975), Irish doctor and writer
• Bill Fitzgerald, news anchor