Credit: ABC Family

One of the things we love most about Pretty Little Liars — besides the show’s often self-reflexive humor and heart-warming friendship between Aria, Spencer, Emily and Hanna is how truly mind-blowingly shocking the series can be. (Seriously, is Ali alive or what?!

Since the show first premiered back in 2010, the writers have kept us on our toes by teasing us with red herrings, sucking us into the Liars’ engaging and often emotional storylines, and providing plenty of surprising twists and turns.

This season has been particularly twist-and-turny, and we love how the drama and tension have heightened to the point where we often are scared (but excited!) to find out what will happen next.

In honor of the Season 4 finale, let’s take a walk down memory lane with a round-up of five of the most shocking Pretty Little Liars finale (and mid-season finale!) moments.

1. Season 2 Finale — Mona’s “A” Reveal

Mona Vanderwaal was always sneaky and self-serving, though we saw a softer and more genuine side of her through her developing relationship with Hanna. Towards the end of Season 2, we even started to really like Mona, as the girls started involving her in top-secret “A” business. Not to mention, she and Spencer shared a sweet moment together outside of the train station when Mona admitted she knew Spencer was smart, but now knew she was “smart smart” thanks to her honest advice not to let Noel get her down. There were a few clues here and there that Mona may not be who we thought she was, like when she effortlessly hacked into the school’s computer to help get Emily a spot back on the swim team, and all of those times she was especially rude to the other Liars.

So when Mona was revealed as “A” in the Season 2 finale, we were definitely shocked! Not only did she totally betray her BFF Hanna, it turns out that flighty Mona was actually a secret super-genius (and total stalker!) with a creepy master plan.

2. Season 2 Finale — The “A-Team” Reveal

During that scary car ride with Spencer in the Season 2 finale, Mona revealed that there was in fact an “A-Team”, and her involvement was only the beginning of a much larger and more sinister project. Not only that, but she threatened Spencer to join, as she thought she’d be a perfect fit for the team. Spooky! The presence of the “A-Team” has definitely been a great development in season 3, further complicating relationships and terrifying the Liars into not knowing who they could trust.

3. Season 1 Finale — Ian’s Murder Attempt

We definitely knew something was up with Ian throughout Season 1, and it wasn’t going to end well. He subtly but scarily threatened Spencer tons of times, all the while setting himself up as a total innocent by marrying and impregnating Melissa, weirdly inserting himself into the Hastings family without warning or much explanation. The Liars were super suspicious of Ian after “A” sent them a creepy video, making it appear that Ian not only dated Alison, but he may have killed her too.

Credit: Twitter

So when the Liars got hold of the then-unknown N.A.T. Club’s creepy and exploitative home videos, Spencer found herself in a life-threatening situation at the town church after Ian realized she knew too much and could use the tape to expose him. In one of the most heart-pounding scenes in Pretty Little Liars history, Ian told Spencer he’d “take care of her” and tried to murder her in the church by throwing her off the bell tower’s ledge! Luckily “A” stepped in and saved Spencer’s life, killing Ian in the process. It was definitely an intense way to end the series, and what made it even more shocking was that “A” might not be the only enemy...or even the enemy at all!

4. Season 2 Mid-Series Finale — The Lady Killer Revealed

We all knew something was fishy about “Nate”, who came to town looking for Emily after his “cousin” Maya’s death. He was short-tempered, weirdly knew a little too much about what Maya was wearing the night she died, and got creepily possessive of Emily after the two shared a kiss — even though he knew Emily was gay! Not to mention he totally overreacted after Jenna rejected his intense advances.

Credit: ABC Family

So when Emily decided to visit “Nate” and his “family” in their creepy, isolated cabin in the woods in the midst of Maya’s murder trial, she found herself in one of the scariest and most thrilling PLL situations ever. “Nate” turned out to be Maya’s killer and stalker, the terrifying Lyndon James, who had plans to murder Paige as some kind of twisted revenge for Emily and Maya rejecting him as a potential boyfriend. Talk about a Nice Guy Gone Bad!

5. Season 2 Mid-Series Finale — Lyndon’s Murder and Caleb’s Near-Death Experience

As if “The Lady Killer” wasn’t intense enough, the season 2 mid-series finale climaxed in a shocking scene where Emily was forced to stab Lyndon to death in self-defense with a knife. And if that trauma weren’t enough, moments Caleb came running up the lighthouse steps to her rescue, only for things to go horribly awry as he had a gun in hand. After stupidly setting down the weapon within dying Lyndon’s reach, Caleb was shot! We’d gotten a glimpse of this heart-pounding scene’s aftermath in the episode’s ambiguous opening, showing Hanna in hysterical tears as an unnamed victim was loaded into an ambulance. Thankfully, it turned out that Caleb survived the shooting, but we didn’t know that until the end of the episode! What a roller-coaster.

What do you think were the most intense PLL finale moments? Do you agree with our list, or do you think we missed more shocking situations? Share below!

Catch the Season 4 summer finale of Pretty Little Liars on Tuesday, August 27, 2013 at 8 p.m. ET/PT on ABC Family.