Darth Plagueis the Wise redesign – his experiments with midi-chlorians have left him twisted and evil, though not necessarily "sickly." At least, his control over his own cells means he doesn't suffer too much from whatever new diseases he's unwittingly created and exposed himself to. I still wouldn't shake hands with him...
Also, the medical droid 11-4D. It's implied he gets rebuilt into one of the bots that puts Darth Vader in his iconic suit, so the design here is meant to look like it could be related to any of them.
