Theodor Loos (1883-1954) was a prolific German actor whose career spanned from silent to sound film. Known for his imposing presence and measured style, he often played roles as intellectuals, nobles, authoritative figures, or complex characters.

Among his most celebrated silent film appearances were those in two masterpieces by Fritz Lang: *Die Nibelungen* (1924), as Giselher, and *Metropolis* (1927), where he played Josaphat. His ability to lend dignity and gravitas to his characters made him a constant presence in pre-war German cinema.

In sound film, he is remembered for his participation in *M* (1931), also by Lang, and numerous other films that consolidated his reputation as a reliable and versatile character actor, active until the 1950s.