Orphan Black (2013)
Tatiana Maslany as Sarah Manning/Cosima Niehaus/Alison Hendrix/Helena/Rachel Duncan/Beth Childs/Krystal Goderitch/MK/Jennifer Fitzsimmons/Katja Obinger... okay, like, a bunch of people. Suggested by D…
You (and your replicas, twins, or doppelgangers) can discuss this poll here!
And speaking of similar, be sure to take this related poll: Favorite Multiple Role Performance