Cinematic 8k wallpaper featuring a colossal Cthulhu towering imposingly near a lighthouse perched on a rugged, moss-covered rock, as a tempestuous sea rages around. The composition is centered, capturing the essence of megalophobia in sharp focus through an extremely detailed 4k digital painting. The creature emanates a subtle organic glow, adding an otherworldly touch to its photorealistic appearance. The dark, moody atmosphere is heightened by lumen reflections dancing on the churning water, with atmospheric lighting and subsurface scattering enhancing the hyperrealism. The scene is rendered in movie quality akin to an octane render using Unreal Engine 5, presenting an insanely detailed, highly realistic image reminiscent of 64k UHD photography, captured with DSLR precision and an 8k sharp focus. The integration of mist swirling around the rock and ethereal light streaming through the storm clouds elevates the mysterious ambiance.