Toronto Defiant is a Canadian professional Overwatch esports team based in Toronto which currently participates in the Overwatch Champions Series. Founded in 2018 as an expansion team for the Overwatch League (OWL), Toronto began play in 2019 and was one of two OWL teams based in Canada. The team is owned by OverActive Media, who also owned the Montreal Rebellion, a former academy team for the Defiant that competed in Overwatch Contenders (OWC).

The Overwatch League (OWL) was a professional esports league for the video game Overwatch, produced by its developer, Blizzard Entertainment. From 2018 to 2023, the Overwatch League followed the model of other traditional North American professional sporting leagues by using a set of permanent, city-based teams backed by separate ownership groups. The league used the regular season and playoffs format rather than promotion and relegation used commonly in other esports and non-North American leagues, with players on the roster being assured a minimum annual salary, benefits, and a portion of winnings and revenue-sharing based on team performance.