Oliver Henry Wallop, 8th Earl of Portsmouth (13 January 1861 – 10 February 1943), was a British peer and also served in the Wyoming State Legislature in the United States. Wallop was born at Eggesford House in Devon, England, to Isaac Newton Fellowes (later Wallop), 5th Earl of Portsmouth, and Lady Eveline Alicia Juliana Herbert, daughter of Henry Herbert, 3rd Earl of Carnarvon. As the third son, he was not expected to inherit his father's earldom, and in 1883 moved to the American West to become a rancher and stockman. He settled in Miles City, Montana, before coming to Big Horn, Wyoming, and purchasing the Canyon Ranch in 1895. He became a United States citizen in 1904 and, as O. H. Wallop, was first elected to the Wyoming Legislature in 1908, serving two terms as a Republican in the Wyo