One of the most peculiar uses of comics in a marketing context, is the Bazooka Joe comic. For roughly sixty years (from 1952 onwards), Topps included a short comic with its Bazooka Joe brand of bubblegum, chronicling the adventures of said Joe and his gang. The original artist, by the way, was Wesley Morse, the creative force behind many of the Tijuana Bibles, small-scale underground comics that parodied major media properties for pornographic purposes.
In 2013, Topps published a hardcover collection of Bazooka Joe’s greatest hits, but @by then the comic strip insert had already disappeared from the packs of gum.
A good example is quickly imitated. In the 1970’s  the Dutch confectionary company Maple Leaf had a Donald Duck brand of bubble gum that also came with a strip featuring the well known Disney Characters. These strips were mostly wordless, so as to strengthen their potential in the multilingual European markets. Packs of Donald Duck gum now fetch high prices on Ebay and other auction sites.
Naturally Marvel could not lag behind, and in 1978, the collaborated with Topps (the same ones that originally introduced the concept) to produce Marvel Bubble Gum. This was a sugar-free alternative, that came with funny comic shorts featuring the Hulk, the Silver Surfer and a host of other Marvel characters. 34 strips were produced in all, and Mostly Comic Art has promised to run them all. Good job!
(With thanks to Mark for the tip)
