Earl Spencer is a title in the Peerage of Great Britain that was created on 1 November 1765, along with the title Viscount Althorp, of Althorp in the County of Northamptonshire, for John Spencer, 1st Viscount Spencer. He was a member of the prominent Spencer family and a great-grandson of the 1st Duke of Marlborough. Previously, he had been created Viscount Spencer, of Althorp in the County of Northamptonshire, and Baron Spencer of Althorp, of Althorp in the County of Northamptonshire, on 3 April 1761.