The University of Western Ontario (UWO; branded as Western University, commonly shortened to Western) is a public research university in London, Ontario, Canada. The main campus is located on 455 hectares (1,120 acres) of land, surrounded by residential neighbourhoods and the Thames River bisecting the campus's eastern portion. The university operates twelve academic faculties and schools. It is a member of the U15, a group of research-intensive universities in Canada.

The university was founded on 7 March 1878 by Bishop Isaac Hellmuth of the Anglican Diocese of Huron as the Western University of London, Ontario. It incorporated Huron College, which had been founded in 1863. The first four faculties were Arts, Divinity, Law and Medicine. The university became non-denominational in 1908. Beginning in 1919, the university had affiliated with several denominational colleges. The university grew substantially in the post-World War II era, and a number of faculties and schools were added.

Western is a co-educational university, with more than 24,000 students, and over 306,000 living alumni worldwide. Notable alumni include government officials, academics, business leaders, Nobel Laureates, Rhodes Scholars, and distinguished fellows. Western's varsity teams, known as the Western Mustangs, compete in the Ontario University Athletics conference of U Sports.