Pretty Little Liars: 8 Possible Twins

Likelihood: Extremely Good

Though the show's Powers That Be have routinely shut down questions about Courtney — Alison's twin sister in Sara Shepard's Pretty Little Liars books — fans of the novels have been waiting for the big reveal since Day 1.

Likelihood: Very Good

Mrs. D is clearly the character that the show wants us to think has a twin. I mean, how else would you explain Alison getting a visit from her dead mother during last week's episode? (Don't forget: Ali's "ghost" once visited Hanna in the hospital, too.)

Likelihood: Decent

Frankly, I completely forgot that Melissa's dead ex ever existed — until a photo posted to Pretty Little Liars' official Instagram account conveniently misspelled the word "villain" as "villian." Get it? "VillIAN"? (Oh, come on, weirder things have happened on this show.)

Likelihood: Why Not?

For that matter, the "Ian" alluded to on PLL's Instagram could also be Ian Harding (aka Ezra).

Likelihood: Decent

There haven't been any major hints about one of the Hastings sisters having a twin, but given their family's penchant for secrets — particularly those related to paternity (Jason!) — would it really surprise you?

Likelihood: Why Not?

Like Spencer and Melissa, there haven't been any red flags raised about Mona having a secret twin, but doesn't it just sound possible? We never really know what is going on in her head.

Likelihood: Long Shot (but let's have some fun anyway)

Aria having a secret sister would be totally insane and completely out of left field — which is exactly why I want it to be true. Indulge my dream theory for a moment: What if Charlotte knew Aria's twin at Radley and threatened to tell her, prompting Byron and Ella — who were out and about the night of Charlotte's death — to do her in?

In that scenario, I'm thinking one of them killed her, and the other threw her off the tower. (But, you know, this is just one editor's daydream.)