Cinematic 8k wallpaper capturing a colossal Cthulhu, positioned prominently near a tall lighthouse on rugged, moss-covered rocks amidst a turbulent sea. The scene is sharply focused and evokes megalophobia, presented as an extremely detailed 4k digital painting. Cthulhu's form exudes a soft, organic glow, imbuing the photorealistic atmosphere with a cinematic, movie-quality depth. The dark and moody ambiance is enhanced by intricate lumen reflections and atmospheric lighting, with subsurface scattering contributing to its hyperrealism. Every element is insanely detailed, achieving a highly realistic and detailed photo quality of up to 64k UHD. The composition embodies the clarity of a high-end DSLR, rendered sharply with the power of Unreal Engine 5 and Octane Render in stunning 8k. Small creative enhancements include swirling mist around the lighthouse and slightly illuminated ocean waves reflecting the creature's glow.