Diet Coke
Diet Coke does not use a modified form of the Coca-Cola recipe, but instead an entirely different formula. The controversial New Coke, introduced in 1985, used a version of the Diet Coke recipe that contained high fructose corn syrup and had a slightly different balance of ingredients. In 2004, Coca-Cola introduced Coca-Cola C2, which it claims tastes much closer to Coca-Cola but contains half the carbohydrates. In 2005, the company introduced Coca-Cola Zero (replaced by "Coca-Cola Zero Sugar" in 2017), a sugar-free variation of regular Coca-Cola.
Coca-Cola Zero Sugar
The move caused some vocal backlash. "The Washington Post" noted Coke Zero is very popular, and that fans compared the change to the launch of New Coke in 1985. However, "Beverage Digest" executive editor Duane Stanford noted that it was very similar in flavor, and that the formula likely was tweaked only slightly as the ingredients list is the same. He noted that the rebranding was the main emphasis.