Five years before “Gangnam Style” covers plagued the internet, Korea caught a severe case of the “Tell Me Virus.” Symptoms included shoulder swaying, exclaiming “Omona!” in surprise while covering one’s mouth, and handsy choreography. The cure was unknown, and everyone from regular folk to celebrities to police officers to even fans in France succumbed to the hysteria, uploading videos of themselves dancing to the Wonder Girls’ single to YouTube and Korean portal Daum.

The South Korean quintet’s song was an immediate hit, and they soon cemented their position as top girl group with the 2008 follow-ups “So Hot” and “Nobody,” which sparked more dance crazes and performed phenomenally on the charts. Wonder Girls were crowned queens of the second generation of K-pop idols and were the first K-pop act to hold a U.S. tour. No one could touch them.

Fans who got into K-pop after 2012, however – when PSY catapulted Hallyu (Korean Wave) onto the world stage – would chiefly know them as a bygone group. By this time, the Wonder Girls were on hiatus after their much-awaited American debut failed to take off and group leader Sunye got married. As a result, groups like Girls’ Generation and 2NE1, who debuted after them, turned into household names and served as the most representative and popular female K-pop acts around the world. Moreover, male group Big Bang held arena concerts in New York and L.A., and Crayon Pop served as Lady Gaga’s opening act two years later. But none of that would’ve been possible without the Wonder Girls, and what they’ve built over their 9-year-long career.

A new K-pop group springs up every day, but none have come close to recreating the Wonder Girls’ signature retro sound and concept, which borrows from the 60’s, 70’s, and 80’s, beginning with the aforementioned “Tell Me.” Though they debuted on February 8, 2007 with “Irony,” it was only after losing rapper Hyuna (now in the group 4minute), gaining member Yubin, and releasing “Tell Me” by that fall that they got popular. The track sampled 80’s staple “Two of Hearts” by Stacey Q, adding a tablespoon of 90’s bubblegum pop sugariness. The catchy English chorus, asking the boy they’re fixated on to tell them that he likes them, is an earworm that will stay longer than Spice Girls’ “Wannabe.”

Given Yubin’s sudden inclusion, the original version of “Tell Me” didn’t feature her rap verses, making “So Hot” her first Wonder Girls single. “So Hot” followed a similar 80’s-influenced formula, but featured a sultrier sound that allowed the girls sexier choreography. And just how hot were the Wonder Girls? “So Hot” became an instant K-pop classic.

But when it comes to breaking Hallyu around the globe, the OG is “Nobody.” After the song became the crown’s third jewel, English, Mandarin, and Japanese versions of the 2008 single followed. On “Nobody,” the Wonder Girls traveled back to the 1960s to channel their inner Motown girl groups concept-wise, while the sound stayed back in the future where rap exists. With big, coiffed hair and glitzy dresses, the Wonder Girls played Dream Girls-like backup singers to the star’s story. “Nobody” followed the catchy “Tell Me” formula, in that it repeated English phrases over and over in the chorus and came with easy-to-follow choreography.

In late 2009, the song’s English version made history by charting at No. 76 on the Billboard Hot 100, making them the first South Korean group to do so. This was, in part, thanks to the Wonder Girls’ other first: opening for The Jonas Brothers’ summer U.S. tour when the Disney boy band was at the height of popularity. And what made entering the chart especially momentous was the fact that they remained true to their signature style, and didn’t change it to appeal to accommodate American audiences. Their own U.S. 20-stop tour followed in 2010.

This is where things changed for the Wonder Girls. Hot off their trifecta of hits, the Wonder Girls moved to New York to pursue a career in the States, neglecting their throne back home. Given that 2009 was a pivotal year in K-pop, this move proved detrimental. Rivals Girls’ Generation released their own viral hit, “Gee,” and followed suit with equally-successful singles while KARA had everyone shaking their butts to “Mister.” Groups like 2NE1, T-ara and 4Minute debuted and gained traction quickly. The competition turned fierce. And not only were the Wonder Girls off in America, member Sunmi then left the group to pursuit her academic studies.

It wasn’t until May 2010 that the Wonder Girls would briefly return to Korea to promote their followup 2 Different Tears EP with new member Hyerim, a release that included both Chinese and English versions. The group took on a disco and ‘80s electro hybrid this time around, while the concept was a mashup of ‘60s mod and the big-haired ‘80s and they played out an Austin Powers-meets-Charlie’s Angels spy story. After one month of promotions in Korea and a short period at No. 1 in the South Korean charts, the girls went back to the U.S. to finish off their tour. “2 Different Tears” failed to chart in the U.S.

After continual delays of their promised American full-length, the Wonder Girls returned to Korea in 2011 and released their second album Wonder World, with “Be My Baby” as the single. This time around, the girls showcased a chic look and their sound was rooted in 90’s pop electronica. They recruited Beyonce’s “Single Ladies” backup dancer Jonte’ Moaning as the video’s choreographer, which is probably why it looks a lot like Queen B’s anthem.

Prior to “Be My Baby,” the Wonder Girls’ songs were fun and youthful. But after two years abroad and with Yubin, Yeeun, and Sunye in their early 20s, the girls came back with a more glamorous and mature concept. Even with the disco influences, "2 Different Tears” sounds like “Nobody.” “Be My Baby,” however, was completely different from anything they’d done before. Wonder World is a pretty solid album, and was penned almost entirely by the members. And while “Be My Baby” wasn’t written by the group, this marks the point where the Wonder Girls transcended from being idols to artists.

But things hit rock bottom in July of that year, when the highly anticipated (seriously, it was three years in the making) American debut song “Like Money,” featuring Akon, dropped. And. It. Sucked. That thing they were so proud of in 2009 — making it in America while staying true to themselves — went out the window, and they released a song that sounded like everything else on the radio at the time. It wasn’t so much that the synth pop song and their outer space robot concept were bad. It just didn’t stand out enough to make a mark.

By November, Sunye went on hiatus from Wonder Girls in order to get married, only to permanently withdraw from the group in December 2014. In 2013, Sohee left the group to pursuit an acting career. Only Yeeun, Yubin, and Hyerim remained, so Wonder Girls took a break.

Speculation that the Wonder Girls were done for, even as their company disputed the allegations, ran amok. But like a phoenix rising from the ashes, the Wonder Girls’ 2015 comeback rocked our worlds just as much as their first hit – quite literally. Even if their instruments were merely props, the Wonder Girls returned from their two-year hiatus as a band. Yubin moved drumsticks around, Yeeun swayed while holding a keytar, Hyerim danced with a guitar in hand, and – get this – former member Sunmi rejoined the group on bass.

In 2015, while everyone in K-pop was drawing inspiration from the ‘90s and trap music, the Wonder Girls went back to their roots: the 1980’s. Reboot draws from nearly every genre popular in said decade, from old school hip-hop to synth rock to sultry electro pop. It was a commercial and critical success, charting at No. 2 on the Billboard U.S. World Albums. The single, “I Feel You” is a breathy, twinkly synth rock song that exudes sensuality and was completely worth the wait. Once again, the members wrote every song except for the single.

Reboot, indeed, gave the Wonder Girls the restart they needed. They practically came back from the dead last year and triumphed without relying on nostalgia, managing to stand out in a time when K-pop competition is vicious. Moreover, the typical shelf life of a K-pop act is about five years — so nine years in the industry is an accomplishment in itself. And even if their girl group crown has long been snatched by others, they’re still very much K-pop legends. With several member changes, leaving Korea for the U.S. for months on end and a hiatus that’s all but eternal in K-pop time, the Wonder Girls have stood the test of time by always releasing high-quality and innovative music and concepts. Add the rest of their accomplishments, and it pretty much solidifies the Wonder Girls’ status as worldwide pop icons we’re not ready to let go of.

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