These were the families of Levi: the Libnite family, the Hebronite family, the Mahlite family, the Mushite family, and the Korahite family. Kohath was the ancestor of Amram.
Korah (son of Izhar), Dathan and Abiram (sons of Eliab), and On (son of Peleth) dared to challenge Moses. (Korah was a descendant of Kohath and Levi. Dathan, Abiram, and On were descendants of Reuben.)