Baron Acton, of Aldenham in the County of Shropshire, is a title in the Peerage of the United Kingdom. It was created on 11 December 1869 for Sir John Dalberg-Acton, 8th Baronet, a prominent historian and Liberal Member of Parliament.

John Emerich Edward Dalberg-Acton, 1st Baron Acton, 13th Marquess of Groppoli,, better known as Lord Acton, was an English Catholic historian, politician, and writer. He is best remembered for the remark he wrote in a letter to an Anglican bishop in 1887: "Power tends to corrupt, and absolute power corrupts absolutely."