Way back before his Teen Wolf days, Tyler Posey popped up in one episode of Smallville.
Way before Timothée Chalamet was winning hearts on the silver screen, he was on Law and Order.
A young Idris Elba made a quick appearance in British comedy show Absolutely Fabulous.
Jennifer Aniston played a charming hospital volunteer in an episode of the sci-fi show Quantum Leap.
Meanwhile, Matthew Perry played a tennis prodigy in the first season of Beverly Hills 90210.
Andrew Garfield has a long filmography, but you may not have noticed his escapades with the 10th Doctor in Doctor Who.
Emilia Clarke's first TV role was on the daytime soap Doctors.
We all know that Ryan Gosling was a Disney kid, but he was also in an episode of Goosebumps.
Pre Step-Up Channing Tatum rocked this look in an epsiode of CSI: Miami.
Before she was Annaliese Keating, Viola Davis was also in an episode of one of CSI's many iterations.
Lady Gaga played a girl who led Tony's son astray in The Sopranos.
Way before he was The Lord of Hell in Lucifer, Tom Ellis was Albert Square's resident GP on Eastenders.
Olivia Colman had a tiny role in the original version of The Office.
Like many other Canadian stars, Shay Mitchell made a lil' appearance in one episode of Degrassi: The Next Generation.
A fresh-faced Brie Larson was in one episode of Ghost Whisperer.
Lil' Leonardo DiCaprio had one uncredited role in Roseanne.
A very young Millie Bobby Brown once gave an emotional performance in Grey's Anatomy.
When it comes to Daniel Kaluuya's early roles, some think of Get Out, some think of Skins, but I bet you don't remember him as Parking Pataweyo; a character in the sketch comedy Harry & Paul.
And Rami Malek made his onscreen debut down in Stars Hollow on Gilmore Girls.
Raven-Symoné was only seven when she made a cameo in The Fresh Prince of Bel-Air, but she was already a pretty big star at that point.
Adam Driver played a creepy guy in Law & Order.
Jennifer Lawrence got her first break playing a mascot in an episode of Monk.
Just a year before becoming a household name as Mike in Stranger Things, Finn Wolfhard was in an episode of Supernatural.
Aubrey Plaza played an NBC Page in 30 Rock not long after leaving the Page Program back in 2006.
When it comes to Matthew McConaughey's filmography, he's really done it all; including a reenactment on Unsolved Mysteries, which was his first credited role.
Long before she was kicking ass, Chloë Grace Moretz was in two episodes of Desperate Housewives.
James McAvoy's first TV role was as a fiesty teenager on The Bill.
Before he was being a creep in YOU, Penn Badgley played a bully in Will And Grace.
And finally, before his silver fox days, George Clooney had a bit part as a detective in an episode of The Golden Girls.
Whose bit part do you remember? Let us know in the comments!