1) Biased one 2) Bigot 3) Bigoted one 4) Bigoted sort 5) Critic, at times 6) Definitely not a fan 7) Execrator 8) Hardly a fan 9) Hardly a yes man 10) Human 11) Hypercritical sort 12) Individual 13) Inimical one 14) Intolerant sort 15) Intolerant type 16) Misanthrope 17) Misogynist 18) Mortal 19) One full of odium Found on https://www.crosswordclues.com/clue/hater
[Internet] Hater is a derogatory term which refers to a person who expresses hatred in public forums, especially those found on the World Wide Web such as YouTube. Haters are distinguished from trolls who seek to attract attention by making provocative comments. Haters may become organised into groups and the seven stage model of hate crime... Found on http://en.wikipedia.org/wiki/Hater_(Internet)