You never forget your first time...at the Met Gala.

Just ask Billie Eilish, who made her debut at the annual star-studded fashion event at New York City's Metropolitan Museum of Art in May 2021.

"It's nuts," the singer, who turned heads at the event with a Marilyn Monroe-like blonde hairstyle and strapless peach Oscar de la Renta gown, said on the Howard Stern Show that December. "It's famous people famous people-ing."

When you get so many celebs together showcasing extraordinary fashion styles, it's not easy to stand out. "Everybody's just embarrassed and insecure about what they're doing and saying," Billie said. "It was amazing though. It just was beautiful in there."

But her favorite part is the lack of fangirling. "What's nice about other people that are in the same kind of world that you're in," she explained, "is they're not getting their phone out and shoving it in your face because they don't want that themselves and that is really relieving."

Billie did go on to attend the two subsequent Met Galas and even snuck in an epic bathroom selfie with fellow celebs at the 2023 event.

The Grammy winner was not the first celeb to break a longstanding no-selfie rule. At the event in 2017, a year after making her Met Gala debut in a sparkling Balmain gown, Kylie Jenner snapped her own group bathroom pics at the bash, featuring stars such as first-time-attendee Paris Jackson, then 19, wore a black Calvin Klein dress.

Zendaya, one of the upcoming 2024 Met Gala co-chairs, was also a teenager when she made her Met Gala debut. At 18, the Euphoria star walked the red carpet at the 2015 event in a custom black and red Fausto Puglisi dress with a short, flared skirt, complete with a long train and sun design embellishments. She went on to attend four more Met Galas before taking a break for half a decade. Now, she is euphoric about her return to the charity ball on May 6 celebrating the museum's "Sleeping Beauties: Reawakening Fashion" exhibit.

"It felt like the right time," Zendaya told E! News' Will Marfuggi at the Challengers premiere in Los Angeles April 16, "to try to go back to the Met."

Look back at more stars' Met Gala debuts.

In Oscar de la Renta

In a Haider Ackermann tuxedo and a Rick Owens turtleneck

In Loewe

In Stella McCartney

In Nicolas Ghesquière

In Atelier Versace

In Thom Browne

In Dundas

In Christian Siriano

In Moschino

In Gucci

In Sam Ratelle

In Jeremy Scott

In Versace

In Calvin Klein

In Balmain

In Fausto Puglisi

In Diane von Furstenberg

Both in Topshop

In Alexander Wang for Balenciaga

In Diane von Furstenberg

In Topshop

In Prada

In Givenchy

In Brooks Brothers (Kevin), Calvin Klein Collection (Joe) and Richard Chai (Nick)

In Chris March (Chrissy) 

In Burberry (Cara)

The Twilight alum wore a black taffeta asymmetrical Chanel spring 2008 Couture gown.

In Donna Karan