The Zerg from Starcraft don't make noises I would call pleasant, and trying to imitate them with a normal human larynx is no easy task. Lucky (?) for us, one fan has our back.
UPDATE: Looks like he removed the video. Ah well.
In the video above, Starcraft fan Alex Paler tries to imitate various Zerg units from Starcraft 2, with belchy yet solid results. Some are better than others (the roach is spot on), but it's pretty impressive considering it's all done in one take into a webcam. Get him a better mic and add some reverb and you'd be gold!
For reference, here are the Zerg units he tried to impersonate:
5. The Queen
11. The Corrupter
12. The Ultralisk
15. The Brood Lord
16. The Broodling
via Alex Paler