I agree with andyRak. The 1st image would be more satisfying if her foot was not cropped out. The mysterious shoe above her is distracting. I do like the pose and the post processing, muted colors.
The 2nd image is also my favorite. I know it can be a challenge to get decent lighting in those low-angle circular group shots without using flash-fill, but you accomplished it!
Picture number 3 has a nice alienating effect with all that negative space behind the cosplayer. The head turned down suggests sadness too, but I am not feeling the emotion well from the expression. The highlights are too washed out. I would like to see more detail of the costume. I think a darker exposure on the cosplayer would add to the emotional direction of this photo.
Your 4th image has some nice action of her hair moving, giving the impression she is walking past the sign. I like that it tells a story, even though it is pushed in our faces with little subtlety. I like the contrast of how clean, grey, and simple the wall is compared to how busy she looks with her leapard skin coat and her firey, red, dread-locked hair.
P.S. ( Her finger obscured the name thor...It could be a little homage to a movie coming soon to theaters near you. ;-)