Dark matter remains one of the greatest mysteries in modern astrophysics and cosmology. Althoughit does not emit, absorb, or reflect light, its gravitational effects provide strong evidence of itsexistence, and observational data prove its presence on galactic and cosmological scales. This paperanalyzes major observational evidence for dark matter: galactic rotation curves, cosmic microwavebackground anisotropies, and gravitational lensing phenomena. It also explains leading theoreticalmodels—Supersymmetry (SUSY), Primordial Black Holes (PBHs), and Weakly Interacting MassiveParticles (WIMPs), and analytically provides their pros and cons. Publicly available data fromESA’s Planck Mission, NASA’s Hubble Telescope, and the THINGS Survey, are used to illustratethe existence of dark matter. The study connects classical physics, cosmology, and modern particletheories to explain the possible nature of dark matter. While none of the models provide completeexperimental confirmation, the combined evidence strongly supports the existence of an unseen,gravitationally dominant component that shapes the universe.