Guardian (The Ark)

The Guardians were the humans who oversaw the Ark's 700 year journey to Refusis II while the rest of Earth's pre-destruction population were kept in miniaturised suspended animation. The Guardians were deposed of by the Monoids. (TV: The Ark)

One of Clara Oswald's splinters wore the clothing of a Guardian. (COMIC: Blood and Ice)

The Book of the War mentioned that the group of early posthuman era Arcadians who had the strongest bio-socio-psycho-emotional link to Earth were the self-termed "guardians". It detailed they were mostly composed of the final generations of survivors from Earth and, in a "ludicrous colonial throwback", were determined to establish themselves on the nearest available Earth-like planet. (PROSE: The Book of the War)

Behind the scenes
Bill Hunter, George Gibbs, Roy Douglas, Trevor Griffiths, Mark Allington, Ron Gregory, Tony Kemp, Judith Webb, Jackie Salt, Jackie Duval, Sheila McGrath, Jan Williams, Terry Cashfield, Diana Chapman, Iris Fry, Hazel Graham, Jacqueline Lewis, Philip Harris, Paul Johnson, John Moyce, Paul Linley, Royston Farrell, Victor Hunt, Alan Norburn, Michael Osborne, Sara Negus, Andrea Beddows, Rosemary Chalmers, Gloria Williams, Rosemary Lord, and Deryn Fisher all had uncredited roles as Guardians. (DWM 228)