It's definitely been the year of Britney, and lots of costumes in the office reflected the singer's many eras ... from "Toxic" to "Slave 4 U." There was also some politics, billionaires and even Kim K at The Met Gala mixed in.

Jake Paul, Jeff Bezos, AOC, Run-D.M.C., Dog the Bounty Hunter, Kanye West, Morgan Wallen, Olivia Rodrigo and Bernie Sanders were all fair game ... and it wouldn't be Halloween 2021 without a 'Squid Game' costume.

Halloween falls on a weekend this year, so be sure to check the website for plenty more celeb looks, haunted parties and holiday treats.