Rocket Raccoon is a strange character with very small beginnings. He first premiered in a backup story in 1976's Marvel Preview #7 by Bill Mantlo and Keith Giffen, where he was introduced as the Guardian of the Keystone Quadrant and head of security for the asylum planet Halfworld, who protected his homeworld with his rocket skates, his ship Rack 'n' Ruin, and his first mate Wal Russ (you guessed it: a walrus). He went on to make rare appearances over the next thirty years, most prominently as a guest star in 1982's The Incredible Hulk #271 and his own four-issue miniseries in 1985.
Rocket Raccoon returned to comics in 2007, in the pages of Annihilation Conquest: Star-Lord by his co-creator Keith Giffen and artist Timothy Green II, where he was reintroduced as a prisoner in a Kree prison, recruited by Star-Lord into a team to liberate the Kree homeworld from the invading Phalanx. Many elements of his original appearances, including his ship, Wal Russ, his rocket skates, and Halfworld were abandoned, and he was instead characterized as a tactical genius with a knack for heavy weapons. He also formed a friendship with the alien tree creature Groot, a relationship that would go on to become a major fixture of his future appearances.
After the end of Annihilation Conquest, Rocket Raccoon went on to become a member of the rebooted Guardians of the Galaxy. He remained a member for the book's entire three-year run, even briefly acting as its leader, until the team was disbanded after Star-Lord's death in 2011's The Thanos Imperative. He then appeared in a series of Rocket Raccoon & Groot backups in the Annihilators and Annihilators: Earthfall miniseries, in which he journeyed to Groot's homeworld Planet X, saved Halfworld from a dangerous inmate's attempted escape, and became an unwitting TV star thanks to intergalactic TV magnate Mojo.
Rocket most recently appeared as a member of the reformed Guardians of the Galaxy in 2012's Avengers Assemble #5, and is slated to appear in a new Guardians ongoing by Brian Michael Bendis and Steve McNiven in 2013, as well as a Marvel Studios Guardians of the Galaxy movie in 2014 and its 2017 sequel. He also appears as a playable character in Ultimate Marvel vs. Capcom 3 and the MMO Marvel Heroes.