The X-Men have had an excellent series of films, so I will be going over which characters appear in the most X-Men films.

Due to X-Men having such a large cast, they often have to resort to certain characters just getting cameos. In order to make things simpler, I will be excluding cameos from the results. The one exception to this rule is Wolverine in X-Men: Apocalypse, because his one scene in the film is a lengthy part of the film instead of just a quick cameo.

The X-Men films include the following films:

1. X-Men (2000)
2. X2: X-Men United (2003)
3. X-Men: The Last Stand (2006)
4. X-Men: First Class (2011)
5. X-Men: Days of Future Past (2014)
6. X-Men: Apocalypse (2016)
7. X-Men: Dark Phoenix (2019)

Spin-off films include the following films:

1. X-Men Origins: Wolverine (2009)
2. The Wolverine (2013)
3. Deadpool (2016)
4. Logan (2017)
5. Deadpool 2 (2018)
6. New Mutants (2020)

Nightcrawler, Iceman, Quicksilver and Deadpool stella, star in three of the films. Nightcrawler appeared in X2, Apocalypse and Dark Phoenix, Iceman briefly appears in X-Men and stars in X2, The Last Stand and the director's cut of Days of Future Past. Quicksilver appears in the three sequels to First Class. Deadpool appears in X-Men Origins: Wolverine and both Deadpool films.

William Stryker appears in X2, X-Men Origins: Wolverine, Days of Future Past and Apocalypse. Rogue stars in the original trilogy and the director's cut of Days of Future Past.

Beast appears in five of the X-Men films. He didn't appear in the first two films, but he appeared in all of the films that followed it.

Jean Grey and Cyclops stella, star in five of the X-Men films (the original trilogy, Apocalypse and Dark Phoenix). Jean Grey also appears in The Wolverine, while Cyclops also appears in X-Men Origins: Wolverine. Other than First Class, Storm stars in all of the X-Men films.

Magneto and Mystique appear in all seven X-Men films.

With the exception of Dark Phoenix, Wolverine appears in all of the X-Men films. He stars in the original trilogy and Days of Future Past. He has a quick cameo in First Class and a lengthy appearance in Apocalypse. He also stars in all three Wolverine films. Professor X appears in all seven X-Men films. He also appears in Logan.

Overall:

Characters that appear in three films: Deadpool, Nightcrawler, Iceman and Quicksilver

Character that appeared in four films: Rogue and William Stryker

Character that appears in five films: Beast

Characters that appear in six films: Storm, Jean Grey and Cyclops

Characters that appeared in seven films: Magneto and Mystique

Characters that appear in eight films: Wolverine and Professor X