7. J
First appearance: 2004 in Ultimate X-Men #41
J is a mutant from a dimension other than 616. As a teenager, he awoke one day, but his mother had vanished without a trace. Also, on the way to school, he couldn’t see anyone. The people he then saw melted before his eyes.
He has the ability
to release a lethal substance that decomposes organic material. Everything around him. The only one who could talk to him was Wolverine. He spent an emotional evening with the teenager before taking care of him (via Marvel Database).
6. Beak
First appearance: 2014 in New X-Men #117
Beak has the abilities of a bird. That sounds better than it is. He has weak bones, can only fly for a short time, has a beak and claws on his hands and feet. This makes him one of the mutants who are visibly different and is socialized as outcast by humans.
Nevertheless, Beak has been involved in some X-Men comics and faced enemies in key moments, even though he stands no chance. Despite his appearance, he is a good soul and a loyal companion to his friends (via Marvel Database).
5. Skin
First appearance: 1994 in Uncanny X-Men #317
As the name suggests, his ability relates to his skin. He has extra skin that he can use elastically. It sounds like Ruffy from One Piece, but it is really just his skin. He does have increased resistance, but his ability is not really useful. At least he can change his face with the extra skin.
In addition, he has gray skin, which he always explains away as a pigmentation disorder in order not to be recognized by mutant haters (via Marvel Database).
4. ForgetMeNot
First appearance: 2011 in X-Men: Legacy #300
ForgetMeNot was involved in many core events of the X-Men, but no one remembers him. His special ability ensures that he is always forgotten. Even Professor X cannot remember him. To counteract this, he has set himself a mental alarm clock that reminds him every hour.
Sure, if you are a thief or want to commit crimes, the ability is definitely useful, but ForgetMeNot can have neither friends nor enemies (via Marvel Database).
