PewDiePie has paid tribute to his arch-enemy Dillon The Hacker after his death aged 20.
The Internet star, whose name was Dillon Henderson, is believed to have passed away last month.
Many fans were convinced online rumours of his passing were a hoax, until PewDiePie seemingly confirmed the news in a tweet today.
He wrote: "Dillon the hacker was such a talented young comedian.
"He successfully trolled my entire audience at one point. Such sad news to hear about his passing.
"My condolences to his family and close ones. RIP Dillon."
Dillon famously feuded with PewDiePie in an online battle that went on for years.
He first started getting attention when he posted a clip titled "PewDiePie roast... PewDiePie sucks!" back in 2014.
In the clip, he shouted at the camera, branding the YouTuber a "joke" and threatened to throw him "in a trashcan". He even called himself PewDiePie's "worst nightmare".
He kept posting the videos, and he regularly insulted the YouTuber, claimed to have taken over his channel and even declared that he'd stolen his girlfriend.
Dillon racked up around 136,000 subscribers to his own channel and nearly 27 million views.
The sad news comes just days after PewDiePie, real name Felix Kjellberg, celebrated a major milestone as he became the first individual YouTuber to reach 100 million subscribers.
PewDiePie also married his longtime girlfriend Marzia Bisognin that same week.
