When one thinks of a slow-burning television show, Pretty Little Liars isn't exactly the first show that comes to mind: the series rolls along like a speeding train, rarely giving you time to process the information that you receive week in and week out before inevitably creating new mysteries and riddles for fans to solve. It's an exhausting, beautiful television show, and as a superfan of the series, I wouldn't have it any other way — even I sometimes have trouble remembering what storylines, characters, and plot twists were significant only several episodes ago. One thing that I definitely put on the back burner are some of the show's guest stars from seasons ago — no matter how recognizable they are now, at that time in Pretty Little Liars history, they weren't anything more than a minor blip in the A game.

Luckily, we now have a little thing called "Netflix," which means revisiting old episodes of Pretty Little Liars is a total breeze. Now that you're no longer worried about the identity of A, you might be able to go back and point out some very familiar faces. Some former Pretty Little Liars cast members made it pretty big after their time ended on the show, and you may have forgotten that they were even on it in the first place.

Here are some guest stars you may have totally forgotten ever showed their face in Rosewood:

1. Diego Boneta

You may recognize Boneta from his recurring role on 90210 or from the movie musical Rock of Ages — but before that, he was playing Spencer's tennis instructor love interest Alex. Boneta's next project? The highly-anticipated horror-comedy series Scream Queens.

2. Carlson Young

Young is best known for playing snarky popular girl Brooke on MTV's Scream, but before that, she was practicing "waiting" in the abstinence club at Rosewood High as Hanna's boyfriend Sean's friend Amber.

3. Robbie Amell

The Tomorrow People star portrayed Noel Kahn's brother Eric in Season 3 of PLL. He's also engaged to Chasing Life's Italia Ricci in real life, because ABC Family keeps it in the... family.

4. Gregg Sulkin

The Faking It actor had a romantic moment with Aria, despite playing her boyfriend Ezra's younger brother Wesley.

5. Natalie Hall

If you were a fan of the "Romeo & Juliet in space" series Star-Crossed, you'll recognize Hall, who played popular girl Taylor. On Pretty Little Liars, Hall was making Hanna's life miserable as her "perfect" step-sister Kate.

6. Patrick J. Adams

Troian Bellisario's fiancé, Suits actor Adams, shared the screen with Lucy Hale and Ian Harding as a friend of Ezra's from college. It wasn't the only time these two showed up on one another's TV shows: Bellisario has a recurring role as Claire on Adams' USA drama.

7. Nathaniel Buzolic

OK, OK: there's no way you already forgot about Buzolic's character Dean, who played Spencer's sobriety coach/maybe-sorta-kinda-love-interest in Season 5 and Season 6. But though you may remember Dean, you might have forgotten where else you recognize him from: Buzolic had a recurring role on The Vampire Diaries and its spinoff series The Originals as Mikaelson brother Kol.

8. Oliver Kieran-Jones

If you recognized cute Brit Colin that Spencer macks on in Season 5, you're not crazy: Kieran-Jones also had an arc on Glee as Kurt's (singing) boyfriend Adam. Not a Glee fan? You may have seen Kieran-Jones as Andrew on Showtime's Episodes.

9. Luke Kleintank

Never forget the days where Travis and Hanna were a thing. You might not recognize Kleintank's name, but if Travis looked awfully familiar, it's because Kleintank made appearances on some of your favorite shows. He played Elliot, Eric's boyfriend, on Gossip Girl for six episodes and Finn on Bones for eight. He recently starred in the film Max and is currently on television series The Man in the High Castle — so if you haven't recognized him yet, you likely will.

Here's hoping plenty of other PLL guest stars break out: there's nothing better than saying we knew them when.

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