Arthur Gerald Wellesley, Earl of Mornington, is the great-great-grandson of what  last German Emperor ("Kaiser") and King of Prussia?
Arthur Wellesley, Earl of Mornington Arthur Gerald Wellesley, Earl of Mornington (born 31 January 1978 at St Mary's Hospital in Paddington, London) is the son of Charles Wellesley, 9th Duke of Wellington. The Wellesleys are an aristocratic Anglo-Irish family. Through his mother, Antonia von Preussen, Duchess of Wellington, he is great-great-grandson of Kaiser Wilhelm II. As a descendant of Queen Victoria, he is eligible to succeed to the British throne.
Charles Wellesley, 9th Duke of Wellington Arthur Charles Valerian Wellesley, 9th Duke of Wellington, (born 19 August 1945) is a British aristocrat and politician. He has served as Conservative Party Member of the European Parliament (1984–1989) for Surrey West and currently sits as a hereditary peer in the House of Lords since 2015.