Which character in wow (warcraft series)...

[Grof]

...was most struggled and suffured ???
For me its obvious Atrhas on 1st place and maybe sylvanas on 2nd place (2 times killed) !!!

[Xiphan]

Wasn't Sylvanas killed 3 times? Once by Arthas, then another by jumping off Icecrown Spire and a third time by Godfrey.

Malygos suffered a lot. Having your flight all but wiped out would be pretty lame.
Illidan suffered and struggled a bunch too, maybe the most. Being imprisoned for 10,000 years for doing what you thought was right (and arguably was) is enough to send the best of us a little crazy, but on top of that there's the whole banishment and hiding from Kil'jaeden and the Adventures deal.

Ner'zhul's a good contender as well - being tortured by Kil'jaeden until eventually your soul is ripped out and bound to armour can't be particular pleasant. Similarly, Bolvar didn't have a very easy life and his undeath must be pretty stressful.

I'd say Thaddius suffered a lot too.

[kingriku]

Easy it was Mankrik, did you see how hard struggled with the loss of his wife and everything in his life destroyed. He went raged and griefed so hard he was performing genocide of the pig people.

[BeastmasterGuardian]

Topper McNabb

This man has suffered since Vanilla.