It was Kelly who died, not Karen.
They've impersonated each other before, and it wouldn't be the first time Pretty Little Liars has done a twin switch.- Jossed in 1x06.
Karen is forced to become a better person
Tying into the above theory, Karen will at first act like Kelly to throw off suspicion and find out what happened. But being "dead" has her hearing what people really thought about her and opening her eyes to what a horribly selfish person she was, which, combined with having to act like her better sister, makes Karen change her own attitude to aid the Liars in the end.- Jossed in 1x06.
Angela Waters' death was murder, not suicide.
People were watching her, but it was dark up there; it could have been very easy for someone to sneak up behind her and shove her. And something clearly happened before the party that night.- Jossed in 1x10.
It's the mothers A is after, not the Liars
A is somehow tied to Angela (perhaps her child) and this entire thing is revenge on what they believe is the Liars' mothers "murdering" her. By tormenting and destroying the daughters first, A wants the moms to feel that pain before going after them.- Jossed in 1x10.
Imogen's baby daddy is a man who sexually assaulted her at the bonfire party.
I actually read about this in an article somewhere, so it's not my personal theory. Anyway, it said that the father of Imogen's unborn child was a guy who sexually assaulted her since she hasn't said anything about him thus far. Besides, if Karen's boyfriend Greg had been the baby's father like I originally thought, then Imogen would've already said as much. The baby being conceived through rape would also explain why the father isn't present and why Imogen wanted to raise the baby with her mother before the latter died.- Confirmed in 1x06.
- Imogen was rape after a different party an few months earlier, but the rapist did attack Tabby at the bonfire
Ash is either A or is connected to Angela somehow.
Every significant character has the letter A in their last name, and Angela has it twice in her first name. Who else has a name that starts with A? Ash.- Jossed in 1x10.
Angela survived and is A, or her mother is A.
Whoever A is, knows too many intimate things about Angela and Liars' mothers from their teenage years. It makes sense of A was there in person or, Angela told them everything, which could be her mother.- Jossed in 1x10.
Chip is the man who sexually assaulted Imogen and Tabby.
Chip was interested in Tabby, his best friend, for years. He's interested in Imogen, eager to be Imogen's partner for the baby in health ed, and goes along with being her baby's father at the adoption agency.- Confirmed in 1x10.
A's framing of the Liars was a Secret Test of Character.
One of the themes in the series is whether or not the daughters are like their mothers. When A framed them for bullying Karen, the plan was to get them all together and see if they'd retaliate. If not, A would leave them alone. When they did, the game went ahead.- Jossed in 1x10.
It was Sherriff Beasley who raped Angela.
He would have been in high school around the same time as Angela and the mothers. Maybe that's why A went after Karen.- Confirmed in 1x09.
A will get plastic surgery on their face.
It’s possible Archie will have to change his face to be able to continue terrorizing the little liars, adults, and any potential bullies, like Chip. The only people who know what A looks like without a mask that’s currently alive is principal Clanton. And since no one else has seen Archie’s face, they wouldn’t be able to recognize him in a new disguise. Knowing that A has a lair for the schemes, it’s possible that A has access to illegal medical practices too. How else was A able to switch Noa’s urine sample without getting caught while making it look real?