Looks mostly lizard and demonic like to me. Does anyone know the original creature it mutated from cuz I doubt it's a demon spawn from hell lolz

Chameleon

Edit: more specifically horned chameleons

They are mutated from chameleons, altho they have lost their color changing ability. If you ever played any of the FO:NV DLC's, it is explained there, in Old worlds Blues I think it is.

Genegineered by the Master.

Doesn't seem so scary:

https://en.wikipedia.org/wiki/Jackson%27s_chameleon#/media/File:Jackson%27s_Chameleon_2_edit1.jpg

Wasn't it a Bioweapon invented by US against China?

They were actually created by the government before the war, the Master gave them a software update.

No, they were created by the pre-war US government, to use against China: http://fallout.wikia.com/wiki/Deathclaw

From Jackson's Chameleons.

They didn't mutate from any one creature. They were a Pre-War experiment by the government that were created in hopes of replacing humans as soldiers during the Great War but the experiments were a failure or they were still working on the them when the bombs fell then, they were further worked on by the MASTER thus making them the incredible killers they are now.

Not all DeathClaws are uncivilized, their was actually an intelligent group of non-aggressive DeathClaws in FO2 you could help.

Pretty sure Avellone even said talking Deathclaws were stupid, though.

I don't know who Avellon is off the top of my head but, yes some were smart and some were as smart as a box of Rocks.

No, no, he said they were a stupid idea.

Edit: he was a developer of the original Fallouts and New Vegas

Oh, sorry I misinterpreted.

LOL, I can't believe I forgot about who Avellon was.