Most disliked Game of Thrones character

[Deborah]

Ramsay Bolton - he's tediously evil without any redeeming features.

[Ken]

A growing number of characters who, through the failings of their author, continue to fail to escape the narrow caricatures they have been written into.

As a counterexample, Jaime Lannister is quite an interesting character, who had developed over the course of the story. Others, like Ned or Bolton, are one-dimensional and poorly written.

[Jevon]

Definitely Jeoffrey. I don't think he died horrible enough.