Cinematic 8k wallpaper featuring a colossal Cthulhu, centered near an ancient lighthouse perched on a moss-covered rock. The sea churns tumultuously beneath dark, brooding skies. Captured in sharp focus, the scene reveals a hyper-detailed 4k digital painting, with Cthulhu's skin exhibiting a faint organic glow. Subtle photorealism blends with movie-quality visuals, evoking a profound sense of megalophobia. The atmosphere is dark and moody, with intricate lumen reflections dancing across the stormy waters. Atmospheric lighting enhances the scene, emphasizing the texture and depth of the environment, while subsurface scattering creates a realistic, almost tangible presence. This ultra-realistic image is crafted with the precision of a 64k UHD DSLR capture, utilizing Unreal Engine 5 and Octane Render to achieve an unparalleled level of detail and cinematic quality in 8k resolution.