I don't see why people are getting so difficult about this issue. Worgen and Goblins exist right now, hence they can be killed and raised as Death Knights no problem. Sure they won't be Gilneas Worgen or Bilgewater Cartel Goblins, but does that matter?

My Forsaken DK I've always played as being simply human, but she was too decomposed and broken to be accepted by human society and so was taken in by the far more tolerant Forsaken. Not a problem lore-wise is it? The same will apply to Goblins and Worgen DKs. They may not have come from that faction originally, but they will end up working alongside them after they escape from the Lich King's grasp. For instance, after the destruction of Kezan, where's a newly-freed Goblin DK really supposed to go? Its basically Steamwheedle or Bilgewater and the Horde-aligned cartels are going to be more acceptable of an undead killing machine Goblin.

Or if you wanted, just say that you're an agent of the Ebon Blade keeping tabs on the faction by virtue of being of same the race. There must be dozens of plausible explanations. People really should stop throwing their rattles out of the pram.

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