Doppelgangers are natural-born shapeshifters that can mimic the shape of humanoid creatures they've encountered. However, their natural form is that of a small hairless humanoid-like creature that possesses spindly limbs, pale brown skin, and a somewhat featureless face that only has two hollow sockets for eyes and a large toothy mouth.

  Due to their inherent ability to shapeshift and mimic other humanoid creatures, Doppelgangers are typically found in areas of relatively dense human populations.

  Their mimicry is rarely perfect and an astute observer can easily discover the signature signs of a doppelganger if they know what to look for. They're relatively harmless creatures that are generally comfortable assimilating into human society, often taking the form of missing children or loved ones with various degrees of success.

  Excerpt from the Book of Ulr:

  "Extreme caution is advised for anyone whose loved ones and/or acquaintances suddenly appear inexplicably strange or unfamiliar. They might very well be a doppelganger in disguise."