Waterloo (, , ) is a municipality in the province of Walloon Brabant, Belgium, which in 2011 had a population of 29,706 and an area of . It is north of Braine-l'Alleud, which is the site of the Battle of Waterloo, where resurgent Napoleon was finally defeated in 1815. Waterloo is a multilingual town; the commune offers services in French, Dutch, and English.