The Hajor were a jellyfish-like species that existed in another dimension.

Their home was severely damaged during the Last Great Time War. After the destruction of the Time Lords, they declared themselves the new Lords of Time. They worked to make the universe stable and smooth out time paradoxes. They allied with Giovanni Lucio since they were sympathetic to his desire for a structured world. The Tenth Doctor helped Valente banish them. (COMIC: The Futurists)