In the James Bond movies and books, "M" was the head of the secret service and "Q"
was the quartermaster... 60's rocker Roy Orbison was known as "The Big O"... there
was the freedom fighter/vigilante "V" in "V For Vendetta"... "J" and "K" were the
"Men In Black"... and in the casino/card club world, lots of places were identified by
a single letter - here are a few examples:

Got any "single letter" items from your collection to share?