Burger King's Whoppers have been popularly marketed as "The King of Burgers." This marketing campaign positions the Whopper as Burger King's flagship and most iconic burger, emphasizing its size, flame-grilled taste, and the idea that it's fit for a "king." Here's an overview of this campaign:

Key Messages:
1. Size and Generosity: The "King of Burgers" campaign underscores the substantial size of the Whopper. It often highlights the idea that it's a burger fit for someone with a hearty appetite.

2. Flame-Grilled Flavor: Burger King distinguishes itself from other fast-food chains by flame-grilling its burgers. The campaign emphasizes the unique taste and flavor profile of the Whopper resulting from this cooking method.

3. Customization: Burger King often promotes the Whopper's customizability. Customers can order it with various toppings and condiments to suit their preferences.

4. Heritage and Iconic Status: The campaign positions the Whopper as an iconic and longstanding offering on the Burger King menu, emphasizing its heritage within the brand.

Advertising and Visuals:
- Advertising materials often feature mouthwatering visuals of the Whopper, showcasing its flame-grilled patty, fresh ingredients, and the signature sesame seed bun.
- Burger King has occasionally introduced limited-time variations of the Whopper, such as the "Angry Whopper" or the "Impossible Whopper" (made with a plant-based patty), to create buzz and excitement around the brand.

Competitive Positioning:
- The "King of Burgers" campaign also serves to position Burger King as a leader in the fast-food industry and a go-to destination for those seeking a substantial, flame-grilled burger.