Legendary YouTuber and lip-sync artist Keenan Cahill has passed away aged 27.
The internet star initially rose to fame all the way back in 2010 when he was just a teenager after posting videos of him lip-synching to popular songs on YouTube.
One of his first-ever videos included him miming along to Katy Perry's 'Teenage Dream', which earned him recognition from the artist herself, before expanding his network of fans to include the likes of Friends star, Jennifer Aniston, rapper 50 Cent and 'Ridin Solo' singer, Jason Derulo.
The video has since been viewed 58 million times since it was posted twelve years ago.
He would go on to become a respected and charming musician in his own right, CNN reports.
Over the years, Cahill managed to rack up over 723,000 subscribers as well as thousands of followers on Instagram and Spotify so the unfortunate news of his passing has really shocked his fans.
The news was initially confirmed by Chicago-based news outlet, WGN9, which reported that the YouTuber and their "close friend" had died on Thursday.
They also added that Cahill was born with Maroteaux-Lamy syndrome which is a progressive condition that causes many tissues and organs to enlarge, become inflamed or scarred, and eventually waste away.
He had a bone-marrow transplant in 1997 in an attempt to halt the progression of the disease, but while it did stop some parts of it, eventually it became too powerful.
In the weeks leading up to his death, the 27-year-old had taken to social media to reveal to his followers that he was undergoing treatment for some serious medical issues.
In a selfie post last year, he told his 21,000 followers that he was "Another surgery down... I’m ok."
Just a few weeks after, he posted another snapshot of his face in which you can clearly see that he's not his usual happy self, alongside the caption: "Last one down."
Both posts received kind messages hoping that the star gets better.
However, it was his final Instagram post that revealed that Cahill was going for an open heart surgery on December 15.
It has now been flooded with tribute messages.
"One of the OG YouTube legends… I remember being in high school stumbling across the lip synch videos and always enjoyed them. Fly high," wrote one user.
"I am saddened by the news of Keenan's passing. He had a sweet spirit and fun energy and brought a lot of joy to people with his YouTube videos. My thoughts and prayers are with his loved ones during this difficult time. May he rest in peace," added another.
A third said: "Core YouTube childhood memories from you. Fly free in the eternal sky."
And one user even took to the comments to tell fans that he died "due to complications" but this news has not been confirmed as of yet.
There has been no official cause of death.
Rest in peace, Keenan Cahill. Our thoughts and prayers are with the family during this incredibly difficult time.