The Simpsons, Shrek, Bratz, and the Pink Panther are among the familiar faces appearing on fatty, sugary and salty products, Which? found.
The consumer group said this was undermining parents' efforts to help children eat healthily.
The Which? Cartoon Heroes and Villains report lists an array of unhealthy products with cartoon characters on the packaging. The Simpsons appeared on honey nut popcorn from Butterkist which is high in sugar.
Spiderman was used on packs of high-sugar Nesquik chocolate flavour cereal.
Bratz characters appeared on packs of Bon Bon Buddies' Fabulous Biscuits, high in fat, saturates and sugar.
Characters from the film Flushed Away appeared on packs of Burton's Jammie Dodgers and on Kellogg's Coco Pops Straws, which are both high in saturates and sugar.
A Happy Feet penguin was used on the box of high-sugar Weetabix chocolate flavour Weetos, and Shrek appeared on packs of sugary Kellogg's Frosties. Winnie the Pooh and Tigger appeared on a selection of products including Marks & Spencer's high-sugar soft fruit gums and Nestle's little chocolate pots, high in both saturates and sugar.
The Pink Panther was used on Northumbrian Fine Foods' Jammy Wheels, which are high in saturates and sugar.
Examples
Which? chief policy adviser Sue Davies said: "There are precious few examples of cartoons being used to promote healthy products.
"Our research shows that the majority are being used to encourage children to eat fatty, sugary and salty foods."
The consumer group praised Disney for recently announcing a ban on their characters being used to promote unhealthy products.
Which? is calling for other firms to follow suit.
It also wants regulation to be brought in to stop `irresponsible' marketing of unhealthy food to children.
But the Food and Drink Federation (FDF), which represents manufacturers, said Britain already had some of the strictest regulations in the world for the promotion of food and drink to children.
And the Advertising Association dismissed the report as out of date. A spokesman said new rules introduced in July prohibit the use of licensed characters and celebrities popular with children in advertisements targeted at children.
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Wor Bobby, Salford Quays (21/08/2007 at 12:27)