Pick a character, choose how they die, and they cannot be resurrected or brought back in any way.
Character: Malfurion Stormrage
Cause of death: Tyrande divorces him causes him to become depressed and succumb to the whispers of the void who promise they can win his beloved back turning him into a void druid that we have to put him out of his (and our) misery once and for all.
Thrall.
Cause of death: We find out even death cannot stop Garrosh, his rage transforms him into an avatar of the old gods. He wipes the floor with thrall who dies sniveling for help.
Faerin Lothar trips on a loose cobble stone. Falls to her left, and unable to catch herself, her head cracks like an egg on the ground.
Brann, trapped in a metal bubble so rigid that any noise he makes reverberates for hours inside. Dies slowly, horribly, and bleeding from his ears.
Calia Menethil
Forsaken Racial
Chromie, forever stuck in a timeloop devoid of time and space rewatching her cringe cinematic with iridikron, she eventually dies from her own cringe self and the world is better off.
Jaina- Due to all her tears and whining during WotLK, her eyes and vital organs have dried up completely. Frost magic has frozen her blood and she dies of raging diarrhea.
Pelagos
He gets teleported back in time to silithus the moment sargeras’ sword comes down, like right beneath where the tip connects
And thats the end of that
Magni, turned into a statue made of Azerite this time. Or I dunno, Sylvanas spontaneously explodes.
Is this about him throwing potions in the webs or yelling “DON’T STAND THERE” for the billionth time? 
Andiun. Do I really need to explain why?
Character: Anduin
Cause of death: Drowning in a river of tears as his own soldiers slice him up for all of his treasonous acts over the years.
Shoulda just stopped at this… woulda been hilariously ironic.
I’d do it myself because he abandoned the throne for some self pity time… alliance had enough of mr whiner.
It’s also about Brann’s tanking style, somehow pulling mobs away while doing 12 dps, and running them out of my aoe.
You, the reader/player.
stabs you in gut through the monitor
Baine Bloodhoof was rescued from Torghast early in Shadowlands and he sat down in Oribos to rest. And he sat… and sat… and sat… Until one day he died.
But, upon his death he was sent back to Shadowlands into the exact same spot where he continues to sit till this very day.
slyvanas
anduin
thrall
jaina
Aethas Sunreaver. Awful character. Not even a fun hate. Just a pathetic, self-pitying whiner. Jaina should have killed him in MoP.
Character: Illidan Stormrage
Cause of death: ends it all after being forced to listen for hours to banal emo snark from someone else for a change.