César Cui (18 January 1835, Vilnius – 26 March 1918, Petrograd) was a Russian composer. He is the least known of the five Russian composers who were nicknamed the "Moguchaya Kuchka" ("Mighty Handful"), a group which included Mily Balakirev, Nikolai Rimsky-Korsakov, Modest Mussorgsky and Alexander Borodin. Cui’s father came from France and his mother from Lithuania.