Number Nine was a Monoid onboard the Ark that served the Monoid Order after the revolution against the Guardians.
According to one account, rather than Monoid Two, (TV: The Ark) Number Nine scouted Refusis II with the Frist Doctor, Dodo Chaplet, and Yendom, before the Refusian Charles killed him in a Launcher. (PROSE: The Ark)