Editor’s Note: Delving into the archives of pop culture history, “Remember When?” is a CNN Style series offering a nostalgic look at the celebrity outfits that defined their eras.

CNN  — 

The scene: The year was 2001 at the Academy Awards. Julia Roberts won Best Actress for her role as Erin Brockovich and celebrated with then-boyfriend Benjamin Bratt. “Gladiator,” “Traffic” and “Crouching Tiger, Hidden Dragon” picked up multiple awards throughout the night. Björk, infamously, wore a dress with a white swan looped around her neck.

The outlandish swan dress may have dominated red-carpet coverage that year, but there’s another ensemble that has become emblematic of the era: Gillian Anderson, at the height of “The X-Files” fame, stepped out for the Vanity Fair Oscars party in a backless navy number with a cheeky surprise. When she turned around, her thong was fully visible, rising up from the ultra-low Eduardo Lucero jersey dress.

Gillian Anderson's fashion choices for the 2001 Vanity Fair Oscars party have become an iconic early 2000s moment.

The “Sex Education” and “The Crown” actor wasn’t the first to wear a visible thong during awards season — a peak-Y2K style that has resurfaced as of late — but stars including Rose McGowan and Halle Berry had done so at the MTV Video Music Awards and MTV Movie Awards in previous years, where sexy and over-the-top reigned.

Anderson’s ensemble, which included effortlessly cool oval shades, stood in stark contrast to the Academy Award outfits of the night, such as Roberts’ black-and-white Valentino dress, and Jennifer Lopez’s voluminous taupe Chanel haute couture gown.

Since then, Anderson’s DGAF whale tail has become iconic, but also misunderstood. The thong has been mistaken for being part of the dress, or being an intentional power move. At a panel at the conference FanX in 2016, Anderson revealed the truth: It was a last-minute decision to avoid a wardrobe malfunction.

Anderson told a panel in 2016 that the thong was a last-minute decision, not a planned style choice.

“I don’t remember how that dress came into my life, and I’m not even sure that I’d tried it on the night before I was going to wear it. But when I put it on, my pubic hairs poked through the dress,” Anderson told the moderator and the audience to raucous laughter. “And there were two solutions… I chose solution number two, which was a thong.”

Updated takes

The new millennium kicked off as the post-Sisqó era, when the R&B singer asked to see more thongs in 1999 and fashion responded in turn with embellished underwear as accessories. Now, a generational shift has occurred as Paris Hilton’s low-slung pants and visible g-strings have given way to Bella Hadid’s updated versions on the same, while Anderson’s styling has been revisited by the likes of Alexa Demie — who arrived to the 2019 “Euphoria” premiere in a backless snakeskin dress and thong embellished with Swarovski crystals — and Hailey Bieber.

Alexa Demie revisited the backless dress and thong pairing at the "Euphoria" premiere in 2019.

At the 2019 Met Gala, Bieber arrived in a shimmering pink Alexander Wang dress with a gem-encrusted g-string detail; Anderson took to Twitter to compare the look with her own throwback moment.

“Another example of necessity being the mother of invention,” she captioned the two images side by side.

As for the fate of the Eduardo Lucero dress, Anderson donated it to a charity auction (sans thong) to benefit research into the genetic disorder Neurofibromatoses, according to her website.

In another peak Y2K-era move, she spoke about the dress and the auction in two different Yahoo! chats with fans that year, answering questions about herself and her charity work.

In one of the chats, just days after the Oscars, user “angiescully” asked her about her style. “I love the dresses you’ve worn to the recent award shows, etc. Do you choose your own dresses? Because if you do, keep going with the bare-back ones!”

Anderson replied that she recently discovered Lucero, “who I love!” she wrote. “He just happens to make some really nice dresses without backs!”