Yeah, there was a one‑off from ’73 called *The Adventures of the Golden Knight* that slipped inside a box of Kellogg’s Corn Flakes. It ran only a single issue, printed on the inside flap, and had a goofy gag where the hero tried to steal the cereal mascot’s power‑up. The publisher—Eclipse Press—had originally planned a whole series, but a PR blunder with a mascot skit made them cancel the run. I found a copy at a yard sale in 2015, and it’s now a little oddity in my file of obscure junk. If you’re hunting for it, you’ll need to scour private collections; only a handful survive.