He, along with Groot, is the breakout star of the new Guardians of the Galaxy movie...
...but Rocket Raccoon had a far more inauspicous debut than most of his co-stars.
It began in Marvel Preview #7 (1976), in the second part of a space opera about a somewhat thick-headed space prince called Sword in the Star, as the lead character looked around on a new world for something to eat...
|That's not Rocket in Panel 3...|
|And, that's not Groot in Panel 3 of this page...|
It was, in fact, the final installment of Sword in the Star.
The "sticky wicket" created by writer Bill Mantlo and artist Keith Giffen was never resolved.
Mantlo explained the problem in a text feature at the end of the issue (which you can click on to enlarge and read)...
When next we saw Rocket Raccoon, it was several years later in the pages of Incredible Hulk (also written by Mantlo)...minus his British accent and without an explanation as to how he survived.
(BTW, Wayfinder also returned...in the pages of the Mantlo-scripted Micronauts, where he travelled into the distant past to become the founder of the Microverse!