Jacob Christian Hansen-Ellehammer (14 June 1871 – 20 May 1946) was a Danish watchmaker and inventor born in Bakkebølle, Denmark. He is remembered chiefly for his contributions to powered flight. Following the end of his apprenticeship as a watchmaker, he moved to Copenhagen where he worked as an electronics mechanic before establishing his own company in 1898. In the beginning he produced cigarette machines, beverage machines and other electronic machinery. In 1904 he produced his first motorcycle, the . The Elleham motorcycle is of step-tru type with the engine situated beneath the seating, thus predating the Vespa scooter by 40 years.