Real name: inapplicable
First Appearance: X-Force #116
While it is unclear whether he is a mutant or an alien being, Doop is the resident mascot and videographer and who records all of the X-Force moments for prosperity, although he has to be constantly reminded that it isn't an art film.
While his intentions (and speech pattern) remain unclear, it is clear that there is much more to this little guy than it may seem. As it is, he has demonstrated the ability to show up when least expected, plus the ability to be unaffected by changes to the time stream.