Yuno Gasai.
In my experience, people, especially fanfic writers will spit blood over how much they hate Yuno. And more often than not, it's only because they're "Die-For-My-Shipers" who seem to think that Yukiteru only liked Yuno for one single reason, often pegging him into the role of a person suffering from Stockholm Syndrome, which is a very shallow interpretation considering the myriad of other factors. Ultimately though they're just making whatever excuse they can think of to reunite poor helpless Yuki with his real true love, who is of course Akise.
I've come to grips with the fact that there is no escape from people who want romantic rival characters to die/shower them with hate/depict them as worse than they really are (in Yuno's case, this gets ridiculous considering she's already really messed up before being exaggerated and made into a caricature. But what actually bugs me about all of it is that they don't care which Yuno it is. They hate the Yuno from the That Yuno was just a normal girl. Besides, I didn't see Akise free Yukiteru from 10,000 years of loneliness and misery. That was all Yuno.