Archduke Carl Ludwig Maria Franz Joseph Michael Gabriel Antonius Robert Stephan Pius Gregor Ignatius Markus d'Aviano of Austria, also known as Carl Ludwig Habsburg-Lothringen (March 10, 1918 – December 11, 2007) was the fifth child of Charles I of Austria and Princess Zita of Bourbon-Parma. He was born in Baden, Austria, and died in Brussels.
During the Second World War, Karl Ludwig and his brother Felix volunteered to serve in the 101st US Infantry Battalion known as the "Free Austria Battalion". However the battalion was disbanded when a number of exiled Jewish volunteers who made up the majority of force ultimately declined to confirm their enlistment. He was buried beside his mother in the Kapuziner Crypt in Vienna.
He was married in Beloeil on 17 January 1950 to Princess Yolande of Ligne (born May 6, 1923). They had four children.