Early Bird Cameo / Literature

• 1-800-Where-R-U: Dr. Cyrus Krantz is namedropped in the "Internal Memorandum" at the end of book 1, well before appearing in person at the end of book 3 and having important roles in books 4 and 5.
• The novella "Cold Snap" by Kim Newman features guest appearances by characters from every novel Newman had published up to that point — and one from An English Ghost Story, the next novel he published after "Cold Snap".
• There's a phenomenon in the Doctor Who Expanded Universe where a new Doctor will cameo in the stories of earlier Doctors before their own series begins. It happened with the Eighth Doctor, who cameoed in the Seventh Doctor's New Adventures before the Eighth Doctor Adventures began; with the Ninth Doctor, who cameoed in the Eighth Doctor Adventures before the revival series began; and with the Thirteenth Doctor, who cameoed in The Missy Chronicles and the "Rose" novelization before her first series.
• Forest Kingdom: The Hawk & Fisher spinoff series' book 4 (Wolf in the Fold) marks the first appearance in Green's work of Razor Eddie, who later becomes a supporting character in the Nightside series.
• Harry Potter:
  • Sirius Black is mentioned in the first chapter of Harry Potter and the Philosopher's Stone. Despite having a pretty important role in the backstory and in Harry's life, he isn't mentioned again until two books later, as the titular character in Harry Potter and the Prisoner of Azkaban.
  • Bellatrix Lestrange first appears in Goblet of Fire in just one scene, the Pensieve flashback to Barty Crouch Jr.'s trial. She isn't named but it's definitely her, as she's bragging about torturing the Longbottoms while also proclaiming undying loyalty to Voldemort. She is a pivotal character in the last three books.
    • Many Death Eaters who become more prominent in the next book, such as Antonin Dolohov and Augustus Rookwood, are also first mentioned in the Pensieve scene, as is Travers who becomes more prominent in the final novel.
  • Mundungus Fletcher is mentioned twice before his first proper appearance in the fifth book: first in the second book trying to hex Arthur Weasley when his back was turned during a Ministry raid of illegally enchanted goods, then in the fourth book trying to get compensated for the destruction of a luxury tent he never owned.
  • The Lovegood family is also mentioned in the fourth book as one of the families at the Quidditch World Cup.
  • Mrs. Figg is mentioned early in the first book, and does not appear (and have her backstory fleshed out) until the fifth.
  • Dumbledore briefly mentions that his brother was once accused of performing inappropriate charms on a goat in the fourth book. The owner of the Hog's Head is mentioned in book 5, as is the fact that the Hog's Head itself smells faintly of goats, and he strikes Harry as being vaguely familiar. It is not until the 7th book that Aberforth Dumbledore appears, and is revealed to be the owner of the Hog's Head.
  • Several creatures in Order of the Phoenix were mentioned in Fantastic Beasts and Where to Find Them prior to their appearances, and even Thestrals earned a minor, blink-and-you'll-miss-it reference under "Winged Horse".
  • Blaise Zabini is mentioned as the last new Hogwarts student to be sorted in Harry Potter and the Philosopher's Stone.
  • Gwenog Jones appeared as a Wizard of the Month (and in Famous Wizard cards) about a year before her book debut in Harry Potter and the Half-Blood Prince.
• Hollow Kingdom (2019): The One Who Opens Doors appears for the first time in the fourth chapter, albeit unidentified as such. He isn't properly introduced for another twenty chapters.
• Johanna Mason gets a brief mention in The Hunger Games, then appears in the flesh (um), a book later. Delly Cartwright is mentioned in the first part of the first book in passing, but doesn't appear until the middle of the third.
• In the James Bond novel Never Dream of Dying, a minion for the Nebulous Evil Organisation The Union visits the client who hired them for their latest Evil Plan for a business transaction. Said Client is one Goro Yoshida, the Big Bad of the next Bond novel The Man with the Red Tattoo.
• Journey to Chaos: Hailey Heleti is fully introduced in Mana Mutation Menace but her first appearance is actually in A Mage's Power. That girl at the head of a girl posse in Roalt castle with the Heleti crest? That's her.
• Liv in the Future: Liv's pet kitten Agent Spaghetti appears in her dream at the beginning of the first chapter before showing up at the pet rental in Chapter 3.
• Mickey Haller, introduced in The Lincoln Lawyer in 2005, might be one of the relatives Harry Bosch met in the flashback featured in The Black Ice in 1993.
• The Mortal Instruments: In Clary's dream in City of Ashes, she sees Jace standing with white wings (a reference to his angel blood) and, behind her, a dark-haired boy with blood-tipped wings - Sebastian.
• In Ranger's Apprentice, there are mentions of a new sail design by a half-Araluen, half-Skandian boy that can sail into the wind, named after the Heron, the boat in which the plan was first included. The Heron and its half-Araluen skirl Hal is the main focus of spin-off series Brotherband.
• Star Trek: New Frontier characters Mark McHenry, Soleta, Tania Tobias and Zak Kebron appear in the TNG prequel series Star Trek: The Next Generation - Starfleet Academy.
• Star Wars Expanded Universe: Poe Dameron, one of the main characters in The Force Awakens, is first mentioned in the epilogue of the novel Moving Target. An additional reference to him is made in the comic book Shattered Empire, which is an Interquel between Return of the Jedi and The Force Awakens.
• The Warcraft novels Tides of Darkness and Beyond the Dark Portal, novelizations of the Real-Time Strategy Warcraft II and its expansion respectively, have this in spades, not only featuring characters from that time period that were only introduced in Warcraft III and beyond, but also updating the story itself in the light of retcons and heavy additions to the canon in later games. They're almost "the Second War as seen through the prism of World of Warcraft". Let's just say that the flashback in The Frozen Throne in which Gul'dan wanders into the Tomb of Sargeras is recited almost verbatim in the first book, and Auchindoun plays a much more extended role in the second, along with the introduction of the "new" draenei.
• Wings of Fire: Qibli debuted as a minor character in The Brightest Night before becoming a main character in the second arc. Additionally, several of the scavengers in Legends: Dragonslayer originally appeared with minor roles in the first arc.

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