Organisation Todt (OT) was a German construction and engineering group founded during the years of the Third Reich. Created by Fritz Todt, the Reichsminister für Rüstung- und Kriegsproduktion, it was attached to the military and was active during WWII.

The main role of the group was to build communications links and defensive structures. Almost all large scale WWII German military structures were built by the group, including armaments factories and concentration camps. The group was responsible for the Atlantic Wall, the submarine pens, and German defences in Italy such as the Gustav Line.

The group was made up of a small number of technical advisors and engineers and an enormous number of foreign workers (1.5 million by 1944). The compulsory labour program for foreign workers was run by Fritz Sauckel.

In 1942, following the death of Todt in an air crash, the group was removed from military control and became part of the central government under the Central Planning Board and Albert Speer.