Nyarlathotep!
All the others are just very powerful Outer Dark entities, but Nyarlathotep (a.k.a. The Giant-Kings’ Moonbeam Messenger, The Serpentmen’s Haunter of The Dark, The Maelstrom of The Isle of Siptah) is an Outer God.
Or maybe it’s Ubbo-Sathla a.k.a. Abhoth, a being that made every living thing on Earth? It’s still active, since we can meet The Emissary of Abhoth in the Volcano biome.