The Whopper is the signature hamburger and an associated product line sold by the international fast food restaurant chain Burger King and its Australian franchise Hungry Jack's. Introduced in 1957, the hamburger has undergone several reformulations, including changes to portion size and bread used. The hamburger is well known in the fast food industry, with Burger King advertising itself as "the Home of the Whopper" and naming its kiosk stores the BK Whopper Bar. In response to the Whopper, Burger King's competitors have developed similar products designed to compete against it.

Burger King sells several variants that are either seasonal or tailored to local tastes or customs. To promote the product, the restaurant occasionally releases limited-time variants. It is often at the center of advertising promotions, product tie-ins, and corporate practical jokes and hoaxes.