Tony the Tiger, and Snap, Crackle and Pop have been branded "cartoon villains" by a U.K. consumer watchdog called Which? for failing to promote healthy eating in children.
Other well-loved characters under fire include Coco the Coco Pops monkey and Quicky the Nesquik Bunny.
The characters were named in a Which? report for not helping with the fight against childhood obesity and poor diet.
Out of 19 children's food company cartoon favorites, not one was found to promote healthier products, researchers for the consumer campaign group found.
The Cartoon League Table was compiled by Which? after a survey found that two-thirds of people believe food companies should not be allowed to use popular characters to advertise unhealthy food.
Among the "cartoon baddies" highlighted by researchers was Moo the Dairylea cow. Which? said manufacturer Kraft's cartoon creation was present across much of Dairylea packaging. But they pointed out that the cheese products are often high in saturated fat and salt.
Dairylea Lunchables chicken 'n' cheese wraps contain more than a third of the maximum amount of salt a 7- to 10-year-old should consume, Which? said.
Tony the Tiger, famed for his "gr-r-reat!" catchphrase, was also ticked off by the watchdog. The long-serving tiger's product Frosted Flakes contain over a third sugar, Which? noted.
Campaigners called for the advertising industry to amend the existing self-regulatory CAP and BCAP codes to encourage firms to use popular characters to help in the fight against childhood obesity and diet-related disease.
"Cartoons are great fun for kids," said Clare Corbett, food campaigner at Which?. "We definitely don't want to see the end of popular characters like Tony the Tiger ... but we do want to see them promoting healthier products."