Oooohhh, I like that.
My least favorite characters in HP are the Dursleys, Umbridge & Peter Pettigrew. I can't say anything nice about them. And I don't know why they are that way and they can't just be nice.
The Dursleys are horrible to Harry and whatever did he do to them? Petunia most likely poisoned the minds of her son & husband to hate Harry because he's Lily's son and she doesn't have a good relationship with her sister.
Umbridge is just a rude and mean (brief) professor at Hogwarts. All she wanted was power and authority and didn't really care for the well being of the students. She just made everyone's lives miserable when she was at Hogwarts for a while.
And Peter...need I say more? He betrayed his friends for what? Because he felt neglected and ignored? That doesn't excuse him for betraying his friends. If I were him, I'd cut them out of my life if they can't seem to support or understand me but there's no need to betray them. Sirius was in Azkaban for 12 years for a crime he didn't commit. James' (and Lily's) death is ultimately because of Peter. And while he didn't directly implicate Remus, Peter's betrayal of James (which led to Sirius being in Azkaban) also impacts him because they were friends.
I know I have more least favorite characters but those are on top of my list.
