Do you have a character that you just "Oh shit" when you hear their name on the character select screen? A character you despise fighting for a multitude of reasons? I have 3:
Ragna - You all know why. Half of XBL plays him, pick up and play monster.
Litchi - A good Litchi player is pretty scary for me, I'm not sure what it is but I just find her difficult. And when you're in the corner against Litchi she becomes a different monster. I have the upmost respect for Litchi players, though. But I just always struggle against her.
Hakumen - Mixed bag. I don't think getting in is too difficult. But respecting mashed out Yukikaze almost nullifies any risky mixup. Same with regular drive anyway. I really have to take it slow here.
Logan / Spencer / Gouki