"Started the day as Baby and ending as Posh," Lily wrote on Instagram Oct. 31. "Spicing up my life this Halloween."
The 35-year-old shared several snaps of her costumes, showing off her blonde pigtail wig for Baby Spice, which she paired with a Spice Girls T-shirt and jeans while giving a shushing pose for the camera. For Posh, Lily traded her blonde tresses for a short, brown bob and opted for an all-black outfit complete with a pencil skirt and blazer. Both looks echoed an iconic Spice Girls photo, which she also shared a photo of.
Lily's fans were obviously obsessed with her dual looks, with one writing, "That's iconic! Double the style, double the fun!"
Another added, "The way that blonde hair looks SO real omg!!!! You look stunning and both styles look impressive on you."
Even the official Spice Girls account showed love for Lily, commenting with two red heart emojis.
But Lily—who has been married to Charlie McDowell since September 2021—didn't only show off her own costumes, as she also took the opportunity to highlight a slew of fans who paid homage to her Emily in Paris character with their Halloween ensembles.
Instagram/Lily Collins
"You guys truly don't disappoint!" Lily shared on Nov. 1, alongside several snaps of fans recreating her character's outfits. "Living for all the @emilyinparis Halloween costumes."
As was to be expected, Halloween 2024 brought out plenty of other iconic getups, like Heidi Klum's take on E.T., which she debuted at her annual Halloween party.
"It took one year to get ready," Heidi told E! News on the red carpet. "We started at 10 a.m. this morning. We just got ready, we just came down."
Heidi's husband Tom Kaulitz also dressed up as E.T. and echoed just what an intense process it was.
"It took a whole team of amazing people," he said. "And lots of planning."
To see more incredible Halloween costumes from this year, keep reading.