Kithriarch was a title in Time Lord society given to the head of each of the families of the Great Houses. The Kithriarch was not the same as the Housekeeper, who was responsible for the well-being of the House itself. The Kithriarch was responsible for the social well-being of each family member.
The position of Kithriarch was retained through regenerations. On the Kithriarch's final death, he would name his successor. Amnoni was the Kithriarch of the House of Blyledge. (PROSE: Cat's Cradle: Time's Crucible) Quences was the Kithriarch of the House of Lungbarrow. (PROSE: Lungbarrow)
Behind the scenes[]
According to Marc Platt, Kithriarchs were viewed as father-figures amongst the Household.