The Lost One (German: Der Verlorene) is a 1951 West German crime drama film directed by Peter Lorre and starring Lorre, Karl John and Renate Mannhardt.

Some scenes were shot at the Wandsbek Studios in Hamburg, while location shooting took place around the city.

Dr. Rothe (Peter Lorre) is a German scientist doing secret research for the Nazi government during World War II.

After the war, Rothe is working under an alias as a doctor for displaced persons.

The film was unsuccessful with most of the German audiences in the 1950s, who tried to forget the Nazi era and preferred Heimatfilme.