Rasmus Otto Mønsted (23 November 1838 - 4 September 1916) was an industrialist and margarine manufacturer from Denmark.
Born at the rural family manor of Lyngsbækgård on Mols near Ebeltoft, Otto Mønsted became a wholesaler of butter, grain and feed in the town of Aarhus in 1865 after some trading experience in Grenå, Roskilde and Copenhagen.
In 1876, he founded a large business exporting butter in hermetically sealed containers to places like England, China and Africa.
He followed five years later with a factory in Godley, near Manchester, England, and in 1894 he built a vast margarine works in Southall, London.
The Otto Mønsted Foundation was created, which contributes to the development of the Danish business community.