William Charles Yelverton, 4th Viscount Avonmore (27 September 1824 – 1 April 1883 in Biarritz), was an Irish nobleman and soldier.
William Charles Yelverton (as he was styled 1824–1870) married, firstly, Maria Theresa Longworth (died 1881) on 15 August 1857 in Rostrevor, County Down, Ireland.
He married, secondly, Mrs. Emily Marianne Forbes (née Ashworth), daughter of Maj.-Gen. Sir Charles Ashworth and Mary Anne Rooke, on 26 June 1858, in Trinity Chapel, Edinburgh, Scotland; Emily Forbes, at the time of the marriage, was the widow of Prof. Edward Forbes, the naturalist.
[1] The validity of his first marriage was tested in the Yelverton case, a 19th-century Irish law case, which eventually resulted in a change to the law on mixed religion marriages in Ireland.
Between 21 February 1861 and 4 March 1861, the trial of Thelwall v. Yelverton found that even though Major Yelverton was a Protestant, and Miss Longworth a Roman Catholic, and though they had been married by a Roman Catholic priest, the marriage was valid.