Millie Bobby Brown Played One Of NCIS' Darkest Characters Before Stranger Things

The final installments of "Stranger Things" are set to hit Netflix in three different episode drops later this year, marking an end to a nearly decade-long saga that transformed the lives of all of its young stars. Fans of the show have seen its child cast grow up in front of our eyes, and at this point, rewatching season 1 feels a bit like stepping into a time machine — to both the '80s and the 2010s.

While season 1's wide-eyed Millie Bobby Brown-Bongiovi, high-pitched Caleb McLaughlin, and baby-faced Gaten Matarazzo have been the subject of countless "before and after" photo comparisons along with their fellow kid cast members, several "Stranger Things" stars actually got their Hollywood starts before being cast in the massive Netflix series. Finn Wolfhard was in an episode of "Supernatural," Sadie Sink popped up in "The Americans," and Noah Schnapp even voiced Charlie Brown in the 2015 Peanuts movie. Yet few pre-"Stranger Things" roles have been quite as unsettling as that of Rachel Barnes, a murderous little girl in a season 12 episode of "NCIS" played by Brown-Bongiovi.

Brown-Bongiovi appears in the "NCIS" episode "Parental Guidance Suggested," and it's clear from the start that she's been cast to play the most adorable elementary school kid in the world (the actress herself was 10 years old during shooting). Early in the episode, the pigtail-wearing kiddo heads home from school alongside another boy her age and his father, all the while making the case for why it's cool to wear a "Harry Potter" costume three Halloweens in a row. When she gets home, Rachel seemingly finds her mother dead of a gunshot wound to the back.

The "NCIS" episode takes its time getting to its big twist, instead using a good chunk of its runtime to endear us further to Rachel. Her dad, we discover, is on a Navy commander on a terrorist hit list, and she's grown up expecting the worst. In one scene, Special Agent Gibbs (Mark Harmon, who starred in the show for its first 18 seasons) lures her out from a hiding spot with popcorn and hot chocolate, then helps her build a fort so she can feel safe. Given his character's own dead daughter (and wife, and mom), this moment is especially sweet. 

Then Rachel is revealed to be the killer.

"Parental Guidance Suggested" seems to pull a bit of inspiration from the 1956 film "The Bad Seed," in which a little pigtail-sporting girl named Rhoda becomes a cold-blooded killer when her dad leaves on military duty. The episode builds on that film's premise by making Rachel's relationship with her father — or lack thereof, since he's gone all the time for work — the source of her deadly misbehavior. Before her death, Rachel's mom was consulting with an infamous serial killer for advice on Rachel's dark impulses, and Rachel ultimately shot her in the back to get her father's attention. Even worse, she shows no remorse when confronted by Gibbs, asking for another juice box even after the stakes are explained to her. Brown-Giovani's effortless performance and an always-freaky killer kid plotline have led some "NCIS" fans to dub Rachel the show's creepiest villain, which is high praise when it comes to a show that's aired 487 episodes to date.