M

As spoken by the Tenth Doctor and the entity possessing Sky Silvestry, M was the thirteenth letter of the alphabet, following L and preceding N. (TV: Midnight)

The logo of McDonald's was a yellow M. (TV: )

In 2012, Henry van Statten ordered that Polkowski be memory wiped and left "on the road" in "Memphis, Minneapolis. Somewhere beginning with M." (TV: Dalek)