Entry #7: The character isn't quite recognizable enough. I think it might because the white hair and white mustache blend into the light background. I think if you play with the colors and outlining it may help. I'm not crazy about the font. It seems a bit too fairytale and feminine.
Entry #6 & 8: I have a smililar issue with this character. There's not enough differentiation in the character.
For all three, they seem like it might appeal to too young of an audience. We're looking for something more edgy.
Please see our updates to the contest brief and contest comments. Hopefully you find something that inspires you. Thanks for your entries! Hope to see more from you!!