Ilya Mikhailovich Lifshitz (Ukrainian : Ілля́ Миха́йлович Лі́фшиць, Russian : Илья́ Миха́йлович Ли́фшиц ; January 13, 1917 – October 23, 1982) was a leading Soviet theoretical physicist, brother of Evgeny Lifshitz. He is known for his works in solid-state physics, electron theory of metals, disordered systems, and the theory of polymers.