Sharing a photo on Instagram, Olympia and her brothers dressed up as famous siblings, The Royal Tenenbaums.
The likeness was picture perfect.
Prince Achileas-Andreas assumed Ben Stiller's role as Chas Tenenbaum in a red Adidas tracksuit, Princess Olympia clipped her blonde lob, wore a polo shirt dress and wrapped herself in a fur coat to play the part of Gwyneth Paltrow’s Margot Tenenbaum, and Prince Constantine Alexios rocked a sweatband, sunnies, fake beard and beige suit as Luke Wilson's Richie Tenenbaum.
“The Greece’s as Royal Tenenbaums,” Olympia’s caption read.
The Princess and Princes of Greece and Denmark weren’t the only royals to get in on the Halloween action.
According to The Mirror, Kate Middleton was spotted shopping at UK supermarket Sainsbury’s in Norfolk with Prince George and Princess Charlotte where they were checking out the Halloween costumes.
Prince Harry and Meghan Markle also shared an Instagram post, hinting that Archie may be going as a little pumpkin.
“Wishing you all a safe and fun Halloween from our family (and our little pumpkin 🎃) to yours!” - TRH,” the Instagram post read.