There are many synonyms for the phrase "grim scary tales". Some potential options might include "terrifying yarns", "horror stories", "bloodcurdling narratives", "spine-chilling sagas", or even "macabre legends". Each of these phrases captures the sense of unease and fear that is often associated with grim and frightening tales. Whether you're looking for spine-tingling horror stories to tell around the campfire or unsettling urban legends to share with friends, there are plenty of synonyms to choose from when it comes to describing these chilling and unnerving narratives. So don't be afraid to explore the darker side of storytelling - just be sure to keep the lights on!