Paraelementals of dust?
--Gibbering Mouther? (First encountered in a ziggurat in Tamoachan, and probably more "madness" than corruption or rot I suppose...still, pretty cool stuff.)--Spawn / Son of Kyuss--Yellow Musk Creeper & Zombies--Rot worms--Mummy (mummy rot's nasty...)I'll keep thinking... I like your idea btw, very intriguing.
Homebrew monster-thing:http://trollandflame.blogspot.com/2010/11/necromould-guest-post.htmlAnd riffing on the elemental theme, how about elementals of fouled water, polluted air, etc.