Unknown. A twentieth-century invention, possibly from a rare Irish surname of obscure meaning, possibly from Dara or Daragh, meaning "oak". It is also the name of an old silver mine near Aberystwyth, Wales.
* The name became popular, particularly in the UK, because of a character in the 1960s American TV series Bewitched, actually spelled Darrin.
* (person with sense of entitlement): As a rhyming equivalent for Karen.