I stumbled across this text listing I created a few months back when I was building my Strange Aeons forces. I have gamed with minis for over 40 years, but had very, very little for this "era" and type of game, so I started looking (as usual) where I could find the figures the cheapest. I found quite a wide variety.
This list is not all-inclusive, nor perfect. This is just a lising of what, I, personally, thought might be some figures that would work with a Cthulhu based miniatures game.
Pathfinder
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Legends of Golarion
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Moon Beast (24)
Serpent folk
Skull and Shackles
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Grindylow (1)
Wrath of Righteous
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Vermelic Demon - mutant holding book
Will-O-Wisp (4) - flying horror
Abrikandilu Demon (15) -
Demoniac - cultist leader
Mongrel (11) - deep one mutant
Invidiak Demon - ?
Gibrileth Demon - flying horror
Locust Demon (#30) - Mi-Go
Vermlek Demon (14) - mutant (no head - maw)
Dominion Invader (48) - crabish/alien (no wings)
Shattered Star
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Nightgaunt (25)
Gug (30)
Alchemical Golem (48)
HorrorClix Nightmares
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Shoggoth #047
[lots and lots more in this old, discontinued range!]
D&D
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Underdark
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Yithian
Dungeons Deep
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Elder Thing (19)
Yithian (27)
Dolgaunt (34)
Mi-Go (20)
Aberrations
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Illithid (half-illithid)
Night Below
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Large Chaos Beast
Demonweb
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Concord Illithid