Halloween is over for another year, but there is still time to enjoy the incredible selection of fancy-dress looks that celebrities have been showing off at star-studded parties and on social media. Seemingly with hours to spend, and a generous budget to play with, many stars have once again gone all out to mark All Hallows' Eve.
Kourtney Kardashian and Travis Barker were among the first to debut their 2021 costumes this year, dressing up as punk couple Sid and Nancy.
American singer Doja Cat kicked off festivities with an underwater-themed birthday party, which a crop of A-list names dressed up and attended, including Billie Eilish who went as a lobster.
Meanwhile, singer Hayley Kiyoko was the first of many to be inspired by Squid Game when it came to her costume this year.
See who wore what for Halloween here:
Already a big fan of dressing up, singer Harry Styles took to the stage for Harryween, a Halloween-themed night on his tour, dressed as Dorothy, from the film The Wizard of Oz.
In a blue gingham dress, red tights, blue socks and red sparkly shoes, Styles even had a ribbon in his hair, as he channelled the character made famous by Judy Garland in the 1939 film.
Justin and Hailey Bieber's selection of costumes
Hailey Beiber turned herself into Britney Spears for Halloween, dressed in a number of the singer's most famous looks. She wore the school girl uniform Spears wore for her breakout song, ... Baby One More Time, her Oops!... I Did It Again red catsuit and replicated the Rolling Stone cover, complete with a Teletubby stuffed toy. Her husband Justin Bieber donned a teddy bear outfit for the occasion.
Earlier in the month, the couple were attendees at Doja Cat's birthday party. The couple dressed up as the king and queen of the ocean, in an image Hailey shared on Instagram.
The Baby singer wore a long silver wig and carried a quindent, while Hailey wore a simple white Grecian gown and crown.
Trevor Noah as The Weekday
Comedian Trevor Noah turned himself in the singer, The Weeknd, but called himself The Weekday, as a nod to his television show, The Daily Show, perhaps.
Lizzo as Baby Yoda
Singer Lizzo took things to a new level by dressing up as Baby Yoda, painting her skin green and donning fake ears and a floor-length coat. In a clip she uploaded to her social media, the singer then walked around in her outfit, even stopping for pictures with passersby.
Chrissy Teigen and John Legend as The Addams Family
Chrissy Teigen, John Legend and their family also got in the spirit by opting for a themed look. They dressed as the Addams Family, with Teigen donning Morticia's look, Legend wearing a centre-parting wig for the role of Gomez Addams, while their daughter Luna took to the role of Wednesday with aplomb. Teigen's mother, Vilailuck, dressed us as Grandmama, while a fifth, unidentified person dressed as Cousin It, in a full-length hair suit.
Reese Witherspoon as Tippi Hedren in 'The Birds'
No, it wasn't a Moira Rose in Schitt's Creek reference, instead actress Reese Witherspoon turned to the 1963 film The Birds for her Halloween inspiration, wearing a pale blue suit, covered in fake crows to channel Tippi Hedren's character Melanie Daniels.
Katy Perry as the Covid-19 vaccine
Vax is the 2021 word of the year, according to the Oxford English Dictionary, and it was also the inspiration for Katy Perry and Orlando Bloom's costumes.
Perry went as the vaccine, while Bloom went as a masked doctor.
"Stay safe guys," Perry wrote on Instagram. The singer was sure to emblazon her name on her costume, so there was no doubt as to who was lurking behind the mask.
Multiple Cruella de Vils
Megan Thee Stallion dressed up as Cruella de Vil, as did Kris Jenner, for an appearance on The Ellen DeGeneres Show. Jenner said she "loved the look" and also shared a photo of herself in a similar Cruella-inspired costume from the 1990s on Instagram.
Tamron Hall as Cardi B and Naomi Campbell
US TV host Tamron Hall donned not one, but two different looks. First, she mimicked a pregnant Cardi B, in a sheer, crystal bodysuit complete with fake baby bump.
Next, she dressed up as model Naomi Campbell circa 1993, when she famously took a tumble on the Vivienne Westwood runway.
Gigi Gorgeous and Luna Mar as Paris Hilton and Kim Kardashian
Canadian blogger Gigi Gorgeous and Mexican singer Luna Mar showed their humorous sides by dressing up as Paris Hilton and Kim Kardashian in matching velour tracksuits.
"Had to recreate this iconic velour tracksuit moment," Gorgeous joked on Instagram.
Chris Appleton as Aquaman
Chris Appleton – hairdresser to Kim Kardashian, Jennifer Lopez and Drew Barrymore – put his hours in the gym to good use transforming himself into the film character Aquaman for the celebrations.
He had the tattoos painstakingly drawn over his torso and even added a long dark wig and fake beard to complete the look, made famous by Jason Mamoa.
Jamie Lee Curtis as Marion Crane
Actress Jamie Lee Curtis channelled her own life, when she dressed up as her mother’s character Marion Crane from the 1960 Alfred Hitchcock film Psycho. Janet Leigh shot to fame for the gruesome shower scene in the film.
Drew Barrymore as her 'Scream' character
Actress Drew Barrymore also referenced the past, by dressing up as her own (short-lived) character from the 1996 film Scream.
Kylie Jenner as ... Kylie Jenner?
Kylie Jenner used the weekend to launch a themed make-up collection, using images of a pre-pregnancy Jenner drenched in fake blood.
Heidi Klum in her own scary movie
Queen of Halloween Heidi Klum went all out once again, this time making her own horror film for the weekend. Known for her love of fancy dress, past outfits have included Princess Fiona from Shrek, Jessica Rabbit from the film Who Framed Roger Rabbit, and even Michael Jackson’s Thriller video.
With her background in modelling, Klum is prepared to spend hours in the make-up chair as specialists apply prosthetics. This year, she went for a demonic theme, complete with creepy make-up and blood-soaked clothes.
Kourtney Kardashian and Travis Barker as Sid and Nancy
Newly engaged Kourtney Kardashian and Travis Barker dressed up as Sid Vicious and Nancy Spungen for early Halloween festivities at the NoCap x Travis Barker House of Horrors on October 19.
Kardashian posted a series of images to her Instagram with the Blink-182 drummer, captioned, "Till death do us part", while Barker wrote: "Throw away the key."
To get into character, Barker wore a studded leather jacket and punk blond wig, and posed with a cigarette. Kardashian also had a blonde wig, which she wore with leather trousers paired with a black mesh top.
Sex Pistols bassist Vicious was accused of fellow musician Spungen's murder in October 1978, however, he died of a drug overdose in February 1979 before the case went to trial.
Doja Cat as Princess Kida
Need To Know rapper Doja Cat threw herself an underwater and Halloween-themed birthday party to celebrate turning 26 on October 21. The guest list included Justin and Hailey Bieber, Winnie Harlow and Billie Eilish.
For the occasion, she dressed up as Princess "Kida" Kidagakash, from Disney's 2001 animation Atlantis: The Lost Empire.
Hayley Kiyoko as Kang Sae-byeok in 'Squid Game'
The first of many celebrity Squid Game costumes, we suspect, singer Hayley Kiyoko dressed up in the series' green and white player tracksuit for an early Halloween celebration.
With the number 067 on her tracksuit, Kiyoko chose to specifically dress up as HoYeon Jung's character Kang Sae-byeok.
The Chance singer wrote on Instagram: "The 067th person to dress up as [HoYeon Jung] in Squid Game for Halloween."
Billie Eilish as a lobster
In keeping with her low-key fashion sense, bad guy singer Billie Eilish, 19, wore a lobster onesie to attend Doja Cat's birthday party.
Winnie Harlow as a siren
For Doja Cat's festivities, model Winnie Harlow dressed up as a siren, the Greek mythological creatures who used their voices to lure sailors on to rocks, causing them to shipwreck.