| ||For an overview of deathclaw variants in the Fallout series of games, see deathclaw.|
|The following is based on Fallout: Brotherhood of Steel and has not been confirmed by canon sources.|
The experimental deathclaws are a group of deathclaws unique to Secret Vault, a Vault-Tec installation which served as the company's ticket to life after the apocalypse. Aside from many scientific projects that were to insure the company's power, some research with radioactive materials and FEV took place there. When the Initiate of Brotherhood of Steel visited the Vault, he encountered unique variants of the beast known all over the wastes.
The Vault-Tec scientists apparently obtained a sample of the deathclaw bioweapon and tried to improve it, using FEV, radiation and technology. The new species became larger, stronger, gaining extra muscle mass and a type of exoskeleton with many protruding spikes. However, the mutation led them to become blind, leaving the deathclaws to rely on their other senses. The longer they live, the bigger they become, so their mutation and the FEV effect could be very similar to that of Capital Wasteland East Coast-type super mutant. The eggs of these deathclaws are also unique, as they appear more like a pile of flesh nearly the same size as human.
Experimental baby deathclaws are easy to kill. They are dark brown, small and their claws are weak and their skin still has no exoskeleton.
The standard version. This experimental deathclaw looks at least a bit like his normal relatives from the West Coast and Capital Wasteland, but much heavier and stronger. This is the version most common in the Secret Vault, between the Baby and the Elder.
The oldest of the experimental deathclaws. They are gray, brutish, and slow. They're much stronger and cause more damage than the normal deathclaw.
Chameleon deathclaw are slightly more evolved than the standard variety. Their adaptive hides help them blend in with their surroundings, rendering them invisible in dark passages. It's weaker than the Elder variety but is much harder to locate and faster.
An extremely unusual prototype variant of an experimental deathclaw. This particular young deathclaw was the subject of an experiment that made him a living colossus. He is the biggest of all deathclaws, possibly all creatures; larger, even, than a super mutant behemoth. It looks exactly like the standard version but three times bigger and stronger. It's presumed that a unique experimental regimen of FEV is to blame, and that the results are intentional. It would seem apparent that the Vault-Tec FEV experimental protocol for this specimen was markedly different from all the others, to result in such a variance of scale and spectrum evident in this multi-story juggernaut. This gigantic deathclaw is known to be a juvenile. FEV also has demonstrated a tendency to cause hosts to continue to grow in bulk and size over a lifetime, a trait evident in the elder experimental deathclaws as well. When taken in consideration with the typical lifespans of both unaltered deathclaws and human mutants, these facts begin to paint a clear and sobering picture of the potential size, power, and destruction that this creature contains, and that the Secret Vault science team attempted to exploit.
The Secret Vault deathclaw mother is gray, big, and has a highly developed exoskeleton. Her head is protected by a natural crown and she has a lot of spikes coming out from her back. She also has a strange ability to regenerate from radioactive pools found in her den, which is probably is result of modified FEV's regenerative features.