The Whisperer is a fictional demon in the prime reality of the Marvel universe of Marvel Comics. Which was created in 1993 by Chris Cooper, first appearing in issue #12 of the 1st volume of Darkhold: Pages from the Book of Sins.
Whisperer is a demon that serves Chthon, an Old One. It has a bipedal insectoid form and is as tall as a human. The demon can be summoned and if the proper blood sacrifices are made (e.g. murdered humans), the summoner gets to ask three questions. In the late 20th century it was summoned by the demon child Diabolique who wanted to know more about Victoria Montesi and her relationship with the Darkhold.