Jens Iverson Westengard (September 15, 1871 – September 17, 1918) was a Danish American legal scholar and diplomat. He was a faculty member at Harvard Law School, first assistant professor (1899–1903), later Bemis Professor of International Law (1915–1918). Between 1903 and 1915, Westengard served as a General Advisor in Foreign Affairs to the Government of Siam.