Lovecraft has such people, directly. Specifically, the professors from the university, in Dunwitch Horror.
Earl Sawyer now took the telescope and reported the three figures as standing on the topmost ridge, virtually level with the altar-stone but at a considerable distance from it. One figure, he said, seemed to be raising its hands above its head at rhythmic intervals; and as Sawyer mentioned the circumstance the crowd seemed to hear a faint, half-musical sound from the distance, as if a loud chant were accompanying the gestures. The weird silhouette on that remote peak must have been a spectacle of infinite grotesqueness and impressiveness, but no observer was in a mood for aesthetic appreciation. 'I guess he's sayin' the spell,' whispered Wheeler as he snatched back the telescope. The whippoorwills were piping wildly, and in a singularly curious irregular rhythm quite unlike that of the visible ritual.
Suddenly the sunshine seemed to lessen without the intervention of any discernible cloud. It was a very peculiar phenomenon, and was plainly marked by all. A rumbling sound seemed brewing beneath the hills, mixed strangely with a concordant rumbling which clearly came from the sky. Lightning flashed aloft, and the wondering crowd looked in vain for the portents of storm. The chanting of the men from Arkham now became unmistakable, and Wheeler saw through the glass that they were all raising their arms in the rhythmic incantation. From some farmhouse far away came the frantic barking of dogs.
The change in the quality of the daylight increased, and the crowd gazed about the horizon in wonder. A purplish darkness, born of nothing more than a spectral deepening of the sky's blue, pressed down upon the rumbling hills. Then the lightning flashed again, somewhat brighter than before, and the crowd fancied that it had showed a certain mistiness around the altar-stone on the distant height. No one, however, had been using the telescope at that instant. The whippoorwills continued their irregular pulsation, and the men of Dunwich braced themselves tensely against some imponderable menace with which the atmosphere seemed surcharged.
Without warning came those deep, cracked, raucous vocal sounds which will never leave the memory of the stricken group who heard them. Not from any human throat were they born, for the organs of man can yield no such acoustic perversions. Rather would one have said they came from the pit itself, had not their source been so unmistakably the altar-stone on the peak. It is almost erroneous to call them sounds at all, since so much of their ghastly, infra-bass timbre spoke to dim seats of consciousness and terror far subtler than the ear; yet one must do so, since their form was indisputably though vaguely that of half-articulate words. They were loud - loud as the rumblings and the thunder above which they echoed - yet did they come from no visible being. And because imagination might suggest a conjectural source in the world of non-visible beings, the huddled crowd at the mountain's base huddled still closer, and winced as if in expectation of a blow.
'Ygnailh... ygnaiih... thflthkh'ngha.... Yog-Sothoth ...' rang the hideous croaking out of space. 'Y'bthnk... h'ehye - n'grkdl'lh...'
The speaking impulse seemed to falter here, as if some frightful psychic struggle were going on. Henry Wheeler strained his eye at the telescope, but saw only the three grotesquely silhouetted human figures on the peak, all moving their arms furiously in strange gestures as their incantation drew near its culmination. From what black wells of Acherontic fear or feeling, from what unplumbed gulfs of extra-cosmic consciousness or obscure, long-latent heredity, were those half-articulate thunder-croakings drawn? Presently they began to gather renewed force and coherence as they grew in stark, utter, ultimate frenzy.
'Eh-y-ya-ya-yahaah - e'yayayaaaa... ngh'aaaaa... ngh'aaa... h'yuh... h'yuh... HELP! HELP! ...ff - ff - ff - FATHER! FATHER! YOG-SOTHOTH!...'
But that was all. The pallid group in the road, still reeling at the indisputably English syllables that had poured thickly and thunderously down from the frantic vacancy beside that shocking altar-stone, were never to hear such syllables again. Instead, they jumped violently at the terrific report which seemed to rend the hills; the deafening, cataclysmic peal whose source, be it inner earth or sky, no hearer was ever able to place. A single lightning bolt shot from the purple zenith to the altar-stone, and a great tidal wave of viewless force and indescribable stench swept down from the hill to all the countryside. Trees, grass, and under-brush were whipped into a fury; and the frightened crowd at the mountain's base, weakened by the lethal foetor that seemed about to asphyxiate them, were almost hurled off their feet. Dogs howled from the distance, green grass and foliage wilted to a curious, sickly yellow-grey, and over field and forest were scattered the bodies of dead whippoorwills.
The stench left quickly, but the vegetation never came right again. To this day there is something queer and unholy about the growths on and around that fearsome hill Curtis Whateley was only just regaining consciousness when the Arkham men came slowly down the mountain in the beams of a sunlight once more brilliant and untainted. They were grave and quiet, and seemed shaken by memories and reflections even more terrible than those which had reduced the group of natives to a state of cowed quivering. In reply to a jumble of questions they only shook their heads and reaffirmed one vital fact.
'The thing has gone for ever,' Armitage said. 'It has been split up into what it was originally made of, and can never exist again. It was an impossibility in a normal world. Only the least fraction was really matter in any sense we know. It was like its father - and most of it has gone back to him in some vague realm or dimension outside our material universe; some vague abyss out of which only the most accursed rites of human blasphemy could ever have called him for a moment on the hills.'
Another is the researcher/student in Lights in the Witch House, who uses his ability to travel via extradimensional spaces to put an end to the witch and her rituals. (But in true lovecraft style, he gets killed HORRIBLY later.)
, who would feel "Right at home" around many of the cosmic horrors that make human minds go totally off the rails. (Or a human that had previously been bodysnatched, who has undergone deep repressed memory hypnotherapy--- The captive minds were given great care and hospitality, and were encouraged to mingle with other captured minds of many of the very beings that Lovecraft uses to shatter minds on sight, after a bit of an acclimation period.)
Investigating a cult of insane elder-god worshiping humans, is EXACTLY what a yithian body snatcher would TOTALLY be down for.