• Heidi Klum’s 2019 Halloween costume is her most gruesome yet.
  • The 46-year-old model documented her scary transformation via Instagram and for New York City residents as she got prepped in a glass window at Amazon.
  • The extensive costume and makeup process went on for several hours, with Klum seen wiggling into a humanoid alien body suit with a team of artists painting on her costume, blow-drying it, and even adding gelatin.
  • Klum was celebrating her 20th Heidiween anniversary, and she marked the occasion with her annual monster bash on Thursday night, showing off her legendary costumes over the years.
  • Visit Insider’s homepage for more stories.

Heidi Klum may have unsurprisingly outdone herself again, dressing up in what’s easily her most gruesome Halloween costume yet.

The 46-year-old model gave the world more than a glimpse of what it takes to claim the title of “The Queen of Halloween” by documenting her extensive several-hour costume and makeup process on Thursday.

Heidi Klum at her Halloween party

Foto: Klum at her 2019 Halloween party.sourceGotham/FilmMagic via Getty

Klum sat down in front of a huge glass window at an Amazon store in New York City, allowing some surprised-looking people to see the star getting the full scary treatment.

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But those who weren't able to see her transformation in the flesh (or full prosthetics, in this case) were able to see all the action via Klum's Instagram as well as on Amazon Live's Instagram stories.

The day before, Klum hinted at her 2019 costume through a spooky video, asking her 6.8 million Instagram followers who she might going as.

Thursday morning then started off with a fresh-faced Klum getting her hair done listening to "Thriller" by Michael Jackson to get her in the mood with the caption "Let's go!"

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The next stage saw Klum try to wiggle her way into a prosthetic body suit while commenting: "It looks like I'm getting into a chicken!" Zac Posen was already quick to comment, asking: "Glowing alien?"

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Things became only slightly clearer when Klum waddled around in the body suit with fans guessing she was "Bride of Frankenstein," "Zombie Kim K," or "ET."

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By lunchtime the model decided to stop for a carb break and said on her Instagram story as she ate spaghetti: "A little bolognese on halloween 'cuz it's a long night and I have heavy weight to carry."

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After her gruesome mask with cut marks was fitted, Klum shared a boomerang of her kissing her husband, Tom Kaulitz, proving love isn't dead ... or is it?

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Her body suit was worked on even more with Klum sharing more videos of the team painting on her costume, blow-drying it, and even adding gelatin to enhance the prosthetic muscles.

In one Instagram story, Klum is heard laughing and asking: "Did I just hear you say you have to cut a hole in my butt?"

Fellow '90s supermodel Naomi Campbell even shared her admiration for this year's costume preparation commenting: "Incredible."

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Acknowledging the long day, one of her Klum's final Instagram posts was captioned "still here" showing the team still working hard at her costume.

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The end result saw Klum looking a bit like a gory alien version of Frankenstein as she made her way through a time capsule to make her big reveal to the world.

The model certainly played up to the part by hissing and glaring at paparazzi, as seen on Amazon Prime Video's Instagram story.

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The star was joined by Klauitz who complemented her futuristic look as an astronaut wearing a broken helmet, making it look as if Klum had broken through and gored his face.

Klum told People back in August her husband's costume was going to be "easier" this year as she "felt so bad for him" last year when he made his Heidiween debut as Shrek and Fiona.

Heidi Klum with husband Tom Kaulitz scaring the paparazzi

Foto: Klum and her husband, Tom Kaulitz, scaring the paparazzi.sourceGotham/GC Images

Klum's other iconic Halloween costumes were also on full display as tiny figures at her legendary monster-bash party on Thursday night, which celebrated her 20 years of spooky festivities.

Fans will remember her going as a 95-year-old woman, "Betty Boop," the werewolf from Michael Jackson's "Thriller" video, "Jessica Rabbit," and even clones of herself.

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The star-studded affair at Cathedralé at the Moxy Village Hotel saw Mariah Carey as an 80s metal player, Neil Patrick Harris and his husband David Burkta as the Olsen twins, and Nicky Hilton as a french maid.

Read more:

Heidi Klum may have outdone herself with her 2018 Halloween costume

28 photos that prove Heidi Klum is the queen of Halloween

Heidi Klum finally revealed her 2017 Halloween costume - and she's totally unrecognizable