Nels Johnson (1838–1915) was a Danish-American professional mechanic and engineer who was the manufacturer of Century tower clocks, commercial tower clocks that were guaranteed for 100 years. The clocks put in business buildings, government buildings, churches, and courthouses. He also repaired nineteenth century machinery as various businesses and made grandfather type tall clocks. He was a businessman and manufacturer associated with commercial shipping, railroad equipment, engine equipment, sawmill machinery, and mechanical devices. His businesses were in Manistee, Michigan. He was also a scientist there and worked with astronomy to learn how to get clocks at different locations to synchronize at the correct time.