Arthur Charles Valerian Wellesley, Marquess of Douro (born August 19, 1945) is the son and heir of Arthur Valerian Wellesley, 8th Duke of Wellington. He has chosen to use the style "Marquess of Douro," though his father in fact holds the peerage "Marquess Douro."

He was born as Earl of Mornington in 1945. He married HRH Princess Antonia of Prussia in 1977, who does not use her royal style.