From our Fan Use and Licensing Q&A:
Q: I want to use the image of an Elder Sign or the Yellow Sign in my work. Is this allowed?
The "Star" Elder Sign is the Chaosium Arcane Symbol, created in 1983 for the second edition of the Call of Cthulhu roleplaying game and is © copyright 1983 Chaosium Inc. The Chaosium Yellow Sign was created by Kevin Ross and is © copyright 1989 Chaosium Inc. nb there are other versions of Lovecraftian elder signs available; these here are the ones that are Chaosium's IP.
The Yellow Sign as seen recently in HBO's '30 Coins'
*if you ask us, we're very likely to say yes.