Religion: mutant supremacist
Alter Ego: Martha Johansson
Other Names: Martha the Mutant Brain; Martha Johannson
First Appearance: New X-Men (vol. 1) #118 (Nov. 2001): "Germ Free Generation, Part 1 of 3"
Super? (Has Super Powers/Special Abilities/Technology): Yes
Number of Appearances: 23
For quite some time, No-Girl and Martha Johansson were thought to be two different people. No-Girl was said to be a mutant who could no be seen or touched; she existed mostly in a "conceptual" state.
No-Girl was said to be in the same Xavier Institute class as Martha Johansson and Basilisk and a few others. Some people thought that "No-Girl" was just an elaborate hoax, a joke or an imaginary friend. Perhaps the student in Xorn's class were simply colluding on a ruse.
Much later, it was revealed that Martha Johansson herself was "No-Girl" all along. There never was a separate, distinct "No-Girl" individual apart from Martha, despite the way the students in her class (or "their class") spoke of "No-Girl.")
So while Martha Johansson is indeed "No-Girl," she does not generally go by this name. She is usually spoken of simply as "Martha."
Suggested links for further research about this character and the character's religious affiliation: