Viscount Simon, of Stackpole Elidor in the County of Pembroke, was a title in the Peerage of the United Kingdom.

[1] It was created on 20 May 1940 for the Liberal politician Sir John Simon.

His second wife Kathleen was a noted campaigner against slavery and other forms of involuntary servitude worldwide, and against racial discrimination.

[2][3] From 1993 to 2021, the title was held by his grandson, the third Viscount, who succeeded his father in 1993.

He died on 15 August 2021 and was survived by his daughter, Fiona, but he had no male heir and the viscountcy became extinct upon his death.