Top 10 One Hit YouTube Wonders
Some people on YouTube became really successful for 1 video & no other video before/after comes close to gaining the success it did.
Known for Baby Shark, which became the second video on YouTube to hit 7 billion views, surpassing Despacito by Luis Fonsi and Daddy Yankee as the most-watched video of all time. No other video on the channel comes anywhere close to Baby Shark. Therefore, Pinkfong became a one-hit wonder on YouTube. It now has over 9.4 billion views, making it the first and only video to ever hit 9 billion views on YouTube.

Known for Despacito, which gained over 7.1B views, no other video by him compares to it. He's a one-hit wonder on YouTube for a reason, and Despacito used to be the most-watched YouTube video for years until Baby Shark by Pinkfong dethroned it in 2020.

Many people remember Crazy Frog for his debut cover of Axel F by Harold Faltermeyer. It became his most successful video and has gained approximately 2.5B views to date. No other video since then has gained the views or success Axel F brought him. Therefore, he's a one-hit wonder both in music and on YouTube.

Anyone with childhood memories of YouTube remembers the Gummy Bear Song. It didn't age well, but it was quite popular back in the day.
He's known for the Gummy Bear Song, which has over 2.2B views, making him a one-hit wonder.

Their song Barbie Girl made them one-hit wonders. It has over 824M views on YouTube, making them one-hit wonders for YouTube as well. No other song or video by them compares.

Her comedy skits have gained millions of views, but the lyric video by Pooh Bear featuring Justin Bieber and Jay Electronica for Hard 2 Face Reality far surpassed them all. It has reached over 214M views to date, making her a one-hit wonder in the YouTube world.
Known for "Sandstorm," which became a popular meme and hit 215 million+ views as of now.
Their song "How Bizarre" made them one-hit wonders worldwide and even on YouTube. Their music video has over 22M views.
Also known as Dytto, she made a video in 2015 dancing with robotic moves to Barbie Girl by Aqua. It has gained nearly 17M views to date. No other video by her has been that successful on any channel, including her personal one.
His most popular video is a tribute to Manfred Mann's song Do Wah Diddy Diddy, which has over 15M views on his channel.
The Newcomers
They released Flatland: The Film, which has just over 1.2 million views as of the time of this comment. All their other videos, uploaded eight years later, only have a couple hundred views.
I think there used to be more videos on the channel, but they also had at most a couple of 10,000 views, as far as I remember.
There's one video on Elton Mendes's channel with 10 million views. It's the Scooby-Doo theme mixed with Demi Lovato's You're My Only Shorty.
She started her YouTube channel on September 24, 2020. In her third video, posted on October 6, she collaborated with Tyler Cameron and discussed her life. This video went viral, getting approximately 861K views in the first 24 hours. It was her first video to pass 1M views, reaching that milestone within days, and now has over 1.9M views.
No other video from her has gained as many views, making her a one-hit YouTube wonder.

They became known for their song Whoomp (There It Is), which was sampled in many songs, including RITMO (Bad Boys for Life) by the Black Eyed Peas (featuring J Balvin) and Whole Lotta Choppas by Sada Baby. These videos and songs gained success that others didn't, making them one-hit wonders.
They were known for their hit You Spin Me Round (Like a Record), which hit #1 on many charts. Even the music video became their most viewed, with nothing else coming close. R.I.P. to the leader Pete Burns.

She has videos on her channel that are more popular than anything David Dobrik ever made. She's only on this list because people associate her with the breakup video, which blew up and made her extra popular.
He achieved one-hit YouTube wonder status on January 9, 2021, with the music video for his latest song, Better Things, which gained over 2M views in 24 hours. Alondra Solivan announced her pregnancy with the video.
He's been on YouTube for a while but gained his top hit status with his 2020 song Plastic, which directly sampled multiple elements from Barbie Girl by Aqua.
Instagram model Francesca Farago went viral on YouTube with her video about breaking up with Kelz. It's her only video on YouTube to hit millions of views, with over 4.3M views to date.

He's posted many vlogs and gained over 18M subscribers. However, one video of his overshadowed all the others. In June 2018, he and Liza Koshy posted a breakup video that shocked the world. It garnered over 17M views in 24 hours, making it their fastest-growing video and David's most viewed video of all time with over 68M views.
It was extremely rare at the time for a video to get nearly 20M views in one day (though now more common with top music artists and Mr. Beast). His second most popular video isn't even half as popular as the breakup video. It became the most watched breakup video on YouTube and the entire internet, as well as the third most watched YouTube video of any kind in 2018. This video definitely made him a one-hit YouTube wonder.

Formerly a cast member of Disney Channel's Austin & Ally and the performer of the theme song for Miraculous Tales of Ladybug & Cat Noir, her all-time signature hit Boombox surpassed 66M views on YouTube. It is her only video to ever pass 10M, 20M, 30M, 40M, 50M, 60M, and more views on YouTube. None of her other videos will ever come close to Boombox, earning her spot on this list.
Her music video for Pink Freak got over 2.1M views, with no other video from her coming even close. She's a one-hit wonder for the YouTube world, but a two-hit wonder in music.

Her "To My Daughter" video got approximately 36M views in 24 hours, and no other video of hers has ever come close. So far, it's her only hit on YouTube. It was the most viewed non-music and non-movie trailer video on YouTube in 24 hours.

Ever since her last song, "Wear It Like a Crown," turned out to be so successful, it's obvious the video for it was her biggest hit. It's her most popular song as a solo artist. Sadly, she lost her battle with breast cancer on September 5, less than six months after she released her song and video. She was 39 years and 9.5 months old, just 2.5 months shy of her 40th birthday. R.I.P. to the most majestic member of Girls Aloud and a true pop princess.
Known for the double rainbow video, which hit 49 million views.
R.I.P. Paul Vasquez, who passed away in 2020.

I feel like some people only know him for the "I'm A Banana" song and haven't really paid attention to the terrible things he's done.