It was also associated with the Doctor's TARDIS, as it was the colour of the police box disguise of the TARDIS. When the Eleventh Doctor sent a blue envelope to Amy Pond and Rory Williams, Amy knew he was the one who sent it, recognising the colour as "TARDIS blue". (TV: The Impossible Astronaut)
Humanoid Daleks, (COMIC: Genesis of Evil) Vogans, (COMIC: The Vogan Slaves) Monstrons (COMIC: The Menace of the Monstrons) Crespallions (TV: The End of the World ) and Zerovians (COMIC: Impasse) had blue skin. Dahh-Ren was also blue (TV: Oxygen), as was Jorj (TV: World Enough and Time), their respective species are unknown.