666 (number)
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666 was a number.
666 was known as "the number of the beast". (PROSE: Warlock [+]Loading...["Warlock (novel)"])
When the Midnight entity possessed Sky Silvestry, Jethro Cane said 666 to see if she would repeat it. (TV: Midnight [+]Loading...["Midnight (TV story)"])
The Tenth Doctor guessed 666 as a security protocol number for the Heavenly Host.