Midnight blue was a dark shade of blue named for its resemblance to the apparently blue colour of a moonlit night sky.
The Eighth Doctor wore an ascot tie of midnight blue dupioni during the Last Great Time War right up to his death. (TV: The Night of the Doctor)
The Third Doctor wore a midnight blue cravat. (TV: The Ambassadors of Death)
Bill Potts wore midnight blue overalls under her navy peacoat. (TV: The Lie of the Land)
The Master wore a midnight blue bow tie. (TV: Survival)
The Tenth Doctor wore a midnight blue shirt when he met Reinette. (TV: The Girl in the Fireplace)
Donna Noble wore a midnight blue scarf when she spoke with Wilf, her grandpa. (TV: Partners in Crime)
A parallel version of the Doctor wore a midnight blue velvet jacket. (PROSE: Sustainable Energy)
The Ringmaster of the Psychic Circus wore a midnight blue frockcoat with rainbow lapels. (TV: The Greatest Show in the Galaxy)