Can you think of anything more scary in FO than a stealthy Deathclaw, as in a Deathclaw with a Stealth Boy effect? Only way i could think this would happen, is if a Deathclaw subspecies somehow retained it's chameleon ability to blend into it's environment, or they were outfitted with stealth technology like the Nightkins. The only group that would be interested in outfitting Deathclaws with stealth suits, would be the Midwestern BoS.

Imagine walking along the wastes, and you hear something, you turn around, and see nothing. You keep walking, and hear the sound again, you turn around just in time to see a Deathclaw towering over you, his claws already in mid swing towards your face.
The Deathclaw had been stalking you, and the first time you turned around to look, he held still and you didn't see him due to the Stealth field on him, when you continued walking, he closed into melee range with you and attacked. Would be a brutally effective assassin.

So.....Mr. Cuddlesworth after he ate the stealth boy?