A highly thermally conductive epoxy compound, and a composition, a material for a semiconductor package, a molded product, an electric and electronic device, and a semiconductor package, each including the highly thermally conductive epoxy compound. The epoxy compound is represented by Chemical Formula 1 below and has at least one mesogenic naphthalene unit. E1-M1-L1-M2-L2-M3-E2  Chemical Formula 1 In Chemical Formula 1, at least one of M1, M2, or M3, which are mesogenic units, is a naphthalene unit. M1, M2, M3, L1, L2, and E1 and E2 are as defined in the detailed description.