Don't give yourself nightmares! The tricephalos (three-heads, three noses, three mouths but four eyes) was common in Celtic folklore, so this carving may be Scottish, Welsh, Irish, Cornish or Breton. The fact that it is oak (not stone) suggests the comparatively late date and makes a northern origin less likely. If you have Celtic blood in you, you should feel it rising when you look at this guy! Even if you don't, you'll find him/them stunning.
Details and more photos.