Who is the x men alter ego?

The X-Men are a team of superheroes, so they don't have one singular alter ego. Each member has their own identity and secret life:

* Professor X: Charles Xavier

* Cyclops: Scott Summers

* Jean Grey: Jean Grey (her alter ego is Marvel Girl, but that's more of a superhero name than a separate identity)

* Beast: Hank McCoy

* Wolverine: Logan (James Howlett is his birth name, but he usually goes by Logan)

* Storm: Ororo Munroe

* Nightcrawler: Kurt Wagner

* Iceman: Bobby Drake

* Colossus: Piotr Rasputin

* Rogue: Anna Marie

And many, many more throughout the X-Men's long history.

Do you have a specific X-Men character in mind? I can tell you more about their alter ego if you do!