Whether it's from D&D (any version) or Pathfinder doesn't really matter, this is lore/flavor intended anyways so I don't need the mechanics. I just need the name of the creature and where I can find its lore.
Due to my own searching thus far and others below confirming what I've found thus far (that probably the vast majority if not entirety of creatures with breath weapons are Dragons) I am also interested in Aberrations with Negative Energy based abilities at all.
This is primarily for use with the Creating New Races rules for Pathfinder. Between that and some of the content from Bloodforge (from Dreamscarred Press) you can have an "aberration-touched" humanoid with a breath weapon. For this particular flavor I was hoping to gear the creature towards Negative Energy and some ungodly eldritch horror in his heritage.