William Wells Addington, 3rd Viscount Sidmouth JP DL (25 March 1824 - 28 October 1913), was a British peer and politician.
Sidmouth was the son of Reverend William Leonard Addington, 2nd Viscount Sidmouth, eldest son of Prime Minister Henry Addington, 1st Viscount Sidmouth.
Sidmouth was Member of Parliament for Devizes between 1863 and 1864.
Lord Sidmouth died in October 1913, aged 89, and was succeeded in the viscountcy by his son, Gerald.