Scaring me wise: Noire.
Reason: I love Noire as much as I love Sumia, Lucina, Tiki and Maribelle. He crazy personae just kinda creeped me out at times. Plus the fact that in the localization they added the fact that it's caused by a so-called "good luck charm" she can put on at anytime also makes it kinda scary as well. The dreams she's appeared in also attribute to that <_<.
Hidious wise: Validar and Excellus. I didn't like Aversa's look all that much since to me she revealed more than Tharja. :/