Tutsi, also called Batusi, Tussi, Watusi, or Watutsi, ethnic group of probable Nilotic origin, whose members live within Rwanda and Burundi. The Tutsi formed the traditional aristocratic minority in both countries, constituting about 9 percent and 14 percent of the population, respectively. The Tutsis’ numbers in Rwanda were greatly reduced by a government-inspired genocidal campaign against them in 1994, however.