Os Time Lords são uma raça , ou pelo menos, uma subespécie distinta de Gallifreyan. Um análogo desta questão seria: "O que os humanos fazem?". Dito isso, o wiki :
Time Lords receive their name for their non-linear perception of time, which allows them to see everything that was, is, or could be at the same time, as shown in the 1996 movie Doctor Who. They developed a culture of custodianship and time-related technologies based on this perception which includes strictly controlled time travel machines (known as "TARDISes") and monitoring devices to travel through time and to prevent time from being subverted or abused – although actual action was described as rare in practice due to their traditional policy of strict non-interference and neutrality. They can act to manipulate timelines of a wide range of events and individuals, so long as they do not cross back into their own timeline.
Então, eles gostam de manter a santidade do tempo presumivelmente por intromissão de outros Time Lords e Daleks.
(NB. Eu só li alguns dos livros. Eu ainda estou para assistir a série de TV.)