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.
Princess Antonia, Duchess of Wellington Princess Antonia of Prussia, Duchess of Wellington, Duchess of Ciudad Rodrigo, Princess of Waterloo, Duchess of Victoria, (born 28 April 1955), is a great-granddaughter of Wilhelm II, German Emperor and the wife of Charles Wellesley, 9th Duke of Wellington.