This may be my new favorite. I loved Surt in the episode "Slimer's Sacrifice" and let's face it, pretty much any episode of anything Ghostbusters related that involves them going into the containment unit is always full of awesome.
Again, like Nexa (and unlike the last image I did -- Theron) I didn't really feel the need to play around with this one. He's an awesomely designed character, and his voice is probably the creepiest in the show (next to the Grundel I think). I also love anything that doesn't have eyes (I popped my horror film cherry on Alien at the tender age of 6 -- probably explains a lot of things too).