question: In addition to his mainstream incarnation, what character made his first appearances in "Uncanny X-Men Annual" #14 and "Uncanny X-Men" #266?
answer: Gambit makes his first appearances in "Uncanny X-Men Annual" #14 (July 1990) and "Uncanny X-Men" #266 (August 1990).
context: Title: Brood (comics)
  Passage: The Brood are a fictional race of insectoid, parasitic, extraterrestrial beings appearing in American comic books published by Marvel Comics, especially "Uncanny X-Men."  Created by writer Chris Claremont and artist Dave Cockrum, they first appeared in "Uncanny X-Men" #155 (March 1982).
  Title: Cerebro's X-Men
  Passage: Cerebro's X-Men are a fictional team of supervillains appearing in American comic books published by Marvel Comics.  The characters appeared in both the "Uncanny X-Men" and "X-Men" series.  They were created and designed by Spanish artist Carlos Pacheco but he officially drew them just once in the cover of "Uncanny X-Men" No. 360 (1998).  The interior art of this issue was done by Chris Bachalo.
  Title: X-Tinction Agenda
  Passage: "X-Tinction Agenda" is a 1990 crossover comic book storyline published by Marvel Comics that ran through "Uncanny X-Men" and its spin-off titles, "X-Factor" and "New Mutants".  "X-Tinction Agenda" not only reunited the X-Men after a prolonged period in which the team had been scattered around the globe (following the events of "Uncanny X-Men" #246-251), but featured the combined might of the three mutant teams for the first time, in their fight against the mutant-exploiting Genoshan government.
  Title: Morlocks (comics)
  Passage: The Morlocks are a group of mutant characters appearing in American comic books published by Marvel Comics.  The characters are usually depicted as being associated with the X-Men in the Marvel Universe.  Created by writer Chris Claremont and artist Paul Smith, they were named after the subterranean race of the same name in H. G. Wells' novel "The Time Machine".  They first appeared as a group in "Uncanny X-Men" #169 (May 1983).  Caliban appeared prior to that (in "Uncanny X-Men" #148), but he was not yet a member of the Morlocks.
  Title: The Tunnelers
  Passage: The Tunnelers were a group of Marvel Comics mutants that is offshoot group of Morlocks.  Created by Chris Claremont and Paul Smith, Masque's first appearance was in "Uncanny X-Men" #169 (May 1983).  Created by Chris Claremont, John Romita, Jr. and Bret Blevins, Cybelle's first and last appearance was in Uncanny X-Men #211 (November 1986).
  Title: Gambit (comics)
  Passage: Gambit (Remy Etienne LeBeau) is a fictional character appearing in American comic books published by Marvel Comics, commonly in association with the X-Men.  The character was created by writer Chris Claremont and artist Jim Lee.  Drawn by artist Mike Collins, Gambit makes his first appearances in "Uncanny X-Men Annual" #14 (July 1990) and "Uncanny X-Men" #266 (August 1990).
  Title: Death of X
  Passage: "Death of X" is a 2016 crossover miniseries published by Marvel Comics.  "Death of X" is part of a series of story arcs that have impacted the Inhumans and X-Men titles after Secret Wars ended and Earth 616 was restored along with being related to the events of the Infinity, Inhumanity, and Inhuman story arcs.  This miniseries event answers the question about what really happened between Cyclops and the Inhumans in the eight-month gap between "Secret Wars" and the All New, All Different lineup of comics.  This limited series event serves as a prequel to the series "Uncanny Inhumans", "Extraordinary X-Men", and Volume 4 of "Uncanny X-Men", along with impacting the plot to "Civil War II: X-Men" and ultimately serving as a precursor to lead into the major crossover event "Inhumans vs. X-Men".
  Title: Days of Future Present
  Passage: "Days of Future Present" is a storyline published by Marvel Comics, appearing in the 1990 annuals of "Fantastic Four", "X-Factor", "New Mutants" and "Uncanny X-Men".  Centered on the appearance of an adult version of the powerful mutant Franklin Richards, it is a sequel to the popular "Days of Future Past" story arc from "Uncanny X-Men" #141–142 (January–February 1981).  The storyline unites the Fantastic Four, X-Factor, the New Mutants, and the remnants of a then-disbanded X-Men against a common foe from a dystopian alternate future.  It features the first appearance of Gambit, and the first encounter between Jean Grey and her alternate future daughter Rachel Summers.  Cyclops' baby son Nathan Christopher Charles Summers and the full-grown mutant antihero Cable are depicted in this story as two separate individuals, although they are subsequently revealed to be one and the same.
  Title: Alternative versions of Gambit
  Passage: In addition to his mainstream incarnation, Gambit has been depicted in other fictional universes.
  Title: Night of the Sentinels
  Passage: Night of the Sentinels is a two-part pilot episode of the 1990s "X-Men" animated series.  It originally aired on October 31 and November 7, 1992.  These episodes feature adaptations of Jubilee's intro story ("Uncanny X-Men #244"), Bolivar Trask's creation of the Sentinels ("Uncanny X-Men #14"), the Mark III Sentinels intro ("Uncanny X-Men #98"), the Mutant Registration Act ("Uncanny X-Men #181"), and anti-mutant hysteria present throughout the mid-to-late 1980s comics.  Introduced in the episode were an X-Men team similar in look and line-up to the early 1990s "" drawn by Jim Lee.  The members of the X-Men introduced compose of Professor X, Cyclops, Beast, Jean Grey, Wolverine, Rogue, Gambit, Storm and Jubilee, as well as an original character, Morph.  The series was originally to premiere over the Labor Day weekend in September; however, due to production delays, it was pushed to the end of October.  The two-parter aired as a "sneak preview" even though it was not considered ready for broadcast.  Therefore, there were many animation errors.  However, the errors were later corrected when FOX re-aired the pilot in early 1993.
citations: Gambit (comics) Alternative versions of Gambit