Rear/Raise its ugly head

This idiom is a metaphor that describes something bad or unpleasant that appears or happens quite suddenly. The origin is obscure, but it first appears in print from around the mid-19th century, although the verb 'rear' meaning to rise up dates from Old English i.e. before 1150, according to the OED. To 'rear up', for example a horse rearing up on its hind legs, is first attested from 1580. Shakespeare used 'rear'd' frequently, together with 'uprear'd'. In Henry VI Part I, Act IV, Scene 7, he writes, 'from their ashes shall be rear'd a phoenix that shall make all France afeard.' In Henry VI Part II, Act III, Scene 2, he describes hair as being 'uprear'd'. It's the 'ugly head' part that is the mystery. Some unknown author must have coined this metaphor, meaning, of course, something bad or unpleasant. The search for who coined it continues.