I'm not sure what you're getting at exactly but it is well known that Blizzard's titles were directly inspired by the Warhammer and Warhammer 40k universes[1].

While the visual similarities haven't causes Games Workshop to complain about infringement from Blizzard (as far as I know) it doesn't mean that Games Workshop isn't complaining about infringement in this or other cases.

[1] http://kotaku.com/5929157/the-making-of-warcraft-part-1