Abraham Lincoln also famously claimed he saw one of these multiple times.  
In William Wilson by Edgar Allen Poe one of these antagonizes the main character when his morals lapse, and Percy Shelley writes about one in Prometheus Unbound and claimed to see one before he drowned.  In Johann Goethe's autobiography Truth and Fiction, he claimed to have seen one of these things approaching him on horseback. Abraham Lincoln also famously claimed he saw one of these multiple times.  For 10 points, identify this literary term from the German for "double walker," which refers to the double of a living person and is sometimes called an "evil twin."
In William Wilson by Edgar Allen Poe one of these antagonizes the main character when his morals lapse, and Percy Shelley writes about one in Prometheus Unbound and claimed to see one before he drowned.  
{doppelgänger} (accept {fetch}, prompt on twin, similar)