Voadam
Legend
Howard and Lovecraft serpent men were the same shared literary creation.I don't think there's even any monsters* that make the jump, beyond the general idea of snake people, but even then, the Yuan-Ti function a lot more like something from the Lovecraftian mythos.

Howard created them in 1929 for the first Kull the Conqueror story then Lovecraft mentions/uses them in Haunter in the Dark in 1936.