An optical film including a polymer including a repeating unit A including a repeating unit represented by the following Chemical Formulas 1 to 3, or a combination thereof; and a repeating unit B derived from a monomer having an unsaturated bond copolymerizable with the repeating unit A, wherein the optical film has a short wavelength dispersion of an in-plane phase-difference value (Re) (450 nm/550 nm) ranging from about 0.81 to about 1.20, and a long wavelength dispersion of an in-plane phase-difference value (Re) (650 nm/550 nm) ranging from about 0.90 to about 1.18: wherein, in Chemical Formulas 1 to 3, the variables R1 to R21 are defined herein.