Heidi Klum As Fiona From 'Shrek'
It's hard to pick just one of Heidi Klum's iconic Halloween costumes.
However, she took her dedication to the spooky holiday to another level (if that's even possible) in 2018, dressing up as Fiona the ogre from "Shrek" at her annual Halloween bash.
Nina Dobrev As Billie Eilish
It's safe to say that Billie Eilish captured the attention of people around the world this year - including celebrities.
One of those celebrities took her love for the "bad guy" musician to another level: Nina Dobrev!
The actress transformed into Eilish for the 2019 Casamigos Halloween bash in Los Angeles.
Jessica Biel & Justin Timberlake As *NSYNC Justin Timberlake & A Microphone
After reacting to a vintage clip of herself dismissively declaring she's not a huge fan of *NSYNC, Jessica Biel turned the tables and dressed up as a vintage Justin Timberlake from his boyband days at the 2019 Casamigos Halloween Party.
Timberlake joined his wife in the Halloween celebrations, dressing up as a singer's sidekick - a microphone.
Lupita Nyong'o As Dionne From 'Clueless'
Lupita Nyong'o is known for her killer fashion sense on and off the red carpet.
However, when it came to her Halloween look in 2018, the "Black Panther" actress pulled out all the stops, dressing up as the iconic Dionne from "Clueless".
From the green contacts to the knee-high socks, Nyong'o had every detail down.
Rihanna (And Her Squad) As Teenage Mutant Ninja Turtles
Leave it to Rihanna to give us one of the best Halloween costumes of all time.
Back in 2014, the songstress was ready to fight crime on the streets of NYC with her squad as the Teenage Mutant Ninja Turtles.
Katy Perry As A Cheeto
This Halloween costume is one for the history books.
Katy Perry had everyone laughing as she showed up to Kate Hudson's annual Halloween party in 2014 as a Cheeto.
Rita Ora As Post Malone
Rita Ora pulled off possibly one of the best Halloween costumes ever in 2018.
The "Anywhere" singer transformed into Post Malone for the KISS Haunted House Party, replicating every tattoo that he has on his body. Talk about dedication!
Harry Styles As Elton John
Harry Styles sparkled in a spot-on Elton John costume while attending the Casamigos Halloween Party in 2018.
The bedazzled look was nearly an exact replica of the "Rocket Man" singer's outfit he wore during a show at L.A.'s Dodger Stadium in 1975.
Bruce Willis & Stephen J. Eads As 'The Shining' Twins
Bruce Willis may seem tough on the inside, but back in 2017, he was a frightening little girl on the outside.
The actor and his assistant Stephen J. Eads dressed as the Grady Twins from "The Shining" while attending M. Night Shyamalan's Halloween party.
Neil Patrick Harris & Family As 'Star Wars: New Hope' Cast
In a galaxy far, far away, Neil Patrick Harris, his husband David Burtka and their two children Harper and Gideon took Halloween to the next level in 2015, dressing up as "Star Wars" characters - including Obi-Wan Kenobi, Princess Leia, Luke Skywalker and Han Solo.
Kim Kardashian & Jonathan Cheban As Sonny & Cher
Back in 2017, besties Kim Kardashian and Jonathan Cheban pulled off the ultimate Halloween costume, channelling Sonny & Cher.
Chrissy Teigen & John Legend As Queen Elizabeth II & Prince Philip
Chrissy Teigen and John Legend were Hollywood Halloween royalty as they dressed up as Queen Elizabeth II & Prince Philip back in 2018.
Ciara & Family As 'Black Panther' Cast
After the wild success of "Black Panther" in 2018, it's no surprise that celebrities took the film as inspiration for their Halloween costume - and Ciara and her family didn't disappoint.
While the "Level Up" singer rocked a spot-on look as heroine Nakia, her husband Russell Wilson dressed up as Black Panther himself, and their two children, Sienna and Future, were mini versions of Nakia and Black Panther.
Joe Jonas & Sophie Turner As Gomez & Morticia Addams
"They're creepy and they're kooky... The Addams family!"
Sophie Turner and Joe Jonas pulled out all the stops for Halloween 2018, dressing up as Gomez and Morticia Addams.
Kylie Jenner As Christina Aguilera
Back in 2016, the Internet couldn't stop talking about Kylie Jenner's near-perfect Halloween costume as Christina Aguilera.
From the black extensions in the blonde wig to the iconic leather chaps, the entrepreneur perfectly channelled the singer's "Dirrty" era.