威廉·皮特，第一代查塔姆伯爵，PC（William Pitt, 1st Earl of Chatham，1708年11月15日－1778年5月11日），英国辉格党政治家。在政府任职国务大臣期间，曾经凭七年战争（又名法国-印第安战争）而声明大噪，后来更出任大不列颠王国首相一职。另外，在下院生涯之中，查塔姆伯爵亦曾被誉为伟大的下院议员（The Great Commoner）。现今美国有多处地方均以查塔姆伯爵命名，当中包括有宾夕法尼亚州匹兹堡、弗吉尼亚州匹兹堡、新罕布夏州的匹兹堡、新泽西州的查塔姆，以及查塔姆大学等等。

William Pitt, 1st Earl of Chatham PC (15 November 1708 – 11 May 1778) was a British statesman of the Whig group who led the government of Great Britain twice in the middle of the 18th century. Historians call him Pitt or Chatham, or William Pitt the Elder to distinguish from his son, William Pitt the Younger, who also was a prime minister. Pitt was also known as The Great Commoner, because of his long-standing refusal to accept a title until 1766.