The Call of Cthulhu is the seminal and celebrated work, while At The Mountains of Madness is the only novella-length work. Both are amazing and provide essential lore for the Mythos, such as The Great Old Ones in CoC and Elder Things and Shoggoth in ATMOM. Can’t go wrong with either!
IDW has been publishing DnD comics for a while now, all the Jim Zub work is under their mantle—and that stuff is top notch.
Mindbreaker is latest, among series like Infernal Tides, Shadows of the Vampire, and Evil at Baldur’s Gate.
Also, do not miss the “Road to Neverwinter” prequel novel—audiobook is excellent. Just finished entire novel and there are a few Easter Eggs that relate to upcoming film.
Jaleigh Johnson, a veteran of Faerun, wrote an excellent DnD novel.
I picked up the “Honor Among Thieves: Official Activity Book” because I can and came across an interesting hint at fantastic creatures we might see.
Aarakora sighting, pg. 13.
He was a legend, his work runs through the collection of every gamer that’s bought a sourcebook in the past several decades. Shame on those tossers that tried to lay Wizards’ missteps at his feet. Rest in Gold Pieces.