Plowking...
For example, Grima Wormtongue in Lord of the Rings. An almost farcical name for this character as it tells the reader exactly what he is.
I am pretty sure this is Gandalf's 'pet' name for him, designed to show Gandalf's contempt for - and opinion of - him. I certainly never read 'Wormtongue' as being part of his given name, any more than 'Evenstar' is a true part of Arwen's name.