Moon is not any Moon. He is THE MOON. 

Following a botched, drunken Celtic ceremony in 12ad Moon is condemned to fall from the sky on a daily basis, brush himself off, attire and arm himself appropriately for the period and fight the forces of the ridiculous on behalf of the UK and it's sainted isles - England, Scotland, Ireland and Wales (regardless of borders or how much each country dislikes each other).

He has no mouth with which to speak, no face with which to emote, if you gve him a coke float he will drink it but no one really knows how. He's a surprisingly good shot and a great sense of humour (perhaps).

After 2000 years of combatting absurdity he has found himself in a world growing more ludicrous, teamed with a homicidal traffic warden by the name of Shades Rodriguez - this ancient authority just tries to get from one end of the day to the next without ruining anything too badly.