Waterloo, city, regional municipality of Waterloo, southeastern Ontario, Canada. Its settlement dates from the early 1800s, when a group of Pennsylvania Mennonites led by Abraham Erb settled along the Grand River. The community was named for the Battle of Waterloo (1815). Part of the Kitchener-Cambridge-Waterloo metropolitan complex, Waterloo is the headquarters of several national insurance companies and has diversified industries. The University of Waterloo (1957) and the Wilfrid Laurier University (1911) are there. Inc. village, 1857; town, 1876; city, 1948. Pop. (2006) 97,475; Kitchener-Cambridge-Waterloo metro. area, 451,235; (2011) 98,780; Kitchener-Cambridge-Waterloo metro. area, 477,160.