Jens Olsen (27 July 1872 – 17 November 1945) was a clockmaker, locksmith and astromechanic who built the famous world clock located in the city hall of Copenhagen, the Rådhus.
Even after ending his apprenticeship and becoming a locksmith Olsen continued to pursue these interests.
In 1897, Olsen became a journeyman and eventually ended up in Strasbourg where he saw the famous clock built by Jean-Baptiste Schwilgué in the cathedral.
« In 1943, when he was 71 years old, and Denmark was under German occupation, the Technological Institute of Copenhagen placed a workshop and staff at his disposal and work on the clock began in earnest.
After his death in 1945 his colleague, Otto Mortensen, took over the project and, after its successful completion in 1955, prepared a detailed monograph.