15. Ernst
Cassandra Nova?
So, we're pretty sure Grant Morrison set up Ernst to be Cassandra Nova with a gray Raggedy-Anne wig, and the X-Men were too stupid to know, just like Clark Kent's co-workers having no idea he's Superman. Why? Cassandra disappeared the same time Ernst appeared. They have similar physical features, and in Here Comes Tomorrow, an alternate future arc, Ersnt was referred to as "Cassandra Ernst" by Martha.
Like Superman, Ernst does have superhuman strength, despite her appearance of twig-like child-like limbs and wrinkly face, with traits like those with progenia. But since Morrison's run has ended, Ernst has been retconned of the Nova persona and has been given her own personality. But the constant in her character's history has been her BFF Martha Johansson, you know, the floating brain with syringes all up in her grill that Ernst leads around on a chain leash. I absolutely love the dichotomy of her powers, but it's also mysterious. With Cassandra Nova's own telepathy, telekinesis, and phasing powers and Martha's superstrength, what other powers are within Ernst's grasp? It's likely that her superstrength comes from the TK, but maybe we'll never know.
Favorite Costume(s): Any ugly sweater and adorable pigtails.