Theodor August Konrad Loos (May 18, 1883 in Zwingenberg – June 27, 1954 in Stuttgart) was a German actor. The son of a watchmaker and instruments manufacturer left prematurely the secondary school and worked three years at an export firm for music instruments in Leipzig, after that at his uncle's, an art dealer, in Berlin. He decided however to become an actor. His theater engagements led him to Leipzig, Danzig and Frankfurt am Main, then to Berlin where he acted from 1912 to 1945 at different theaters. Since 1913 he co-operated in more than 170 feature films, initially silent films. Next to its extensive film activity, in the 1930s he could be seen in many performances at the classic theater, over 400 in Peer Gynt alone. After end of the war, he played again more theater. Since August 1949 he was a member of the Staatstheater Stuttgart. The two sons from his marriage died in the second world war.