Midnight blue

Midnight blue is a dark shade of blue named for its resemblance to the apparently blue color 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)