Harold Malcolm Westergaard (9 October 1888 in Copenhagen, Denmark – 22 June 1950 in Cambridge, Massachusetts, United States) was a Danish structural engineer.
He was Professor of theoretical and applied mechanics at the University of Illinois in Urbana and of Civil Engineering at Harvard.
He continued his practice in reinforced concrete in Hamburg, London, Göttingen, and prepared his written dissertation at Königlich Bayerische Technische Hochschule München in 1915.
He obtained a PhD at the University of Illinois in Urbana in 1916 and was appointed lecturer there for theoretical and applied mechanics.
In 1936 professor Westergaard was appointed to the Gordon McKay professorship for structural engineering at Harvard University.