From the 1939 Harlem Jay-Z look-alike to the cover image on a vintage Cosmopolitan bearing a striking resemblance to Amy Poehler, historical celebrity look-alikes are popping up everywhere.

Here are 7 celebrity doppelgangers from various periods of history. The question is: Are these people merely doppelgangers or could they be time travelers?

1. Amy Poehler
2. Jay-Z
3. Keanu Reeves
4. Michael Cera
5. Nicholas Cage
6. Peter Dinklage
7. Sylvester Stallone

What other celebrity doppelgangers have you found? Let us know in the comments below.