An imposter.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.

An imposter, replica, or fake.

an impostor

an imposter or a liar who is pretending to be someone else

An imposter.

An imposter or a fake