We explore the ultimate fate of the universe by examining three major scientific theories: the Big Crunch, where gravity halts and reverses expansion, collapsing the universe into a singularity; the Big Freeze, where accelerated expansion leads to a cold, dark, and energy-depleted cosmos; and the Big Rip, a scenario where dark energy grows stronger and eventually tears apart galaxies, stars, planets, and even atoms. While the Big Freeze is currently the most widely accepted model, ongoing research into dark energy may reshape our understanding of the cosmos’s end.