Nye Frankie Newman, a 17-year-old from Guildford in the UK, passed away after an accident on a Paris Metro on New Year's Eve.
Newman was part of a ten-man troupe of thrill seekers called Brewman, which made headlines in early December after members "surfed" the Paris Metro.
The exact circumstances of the boy's death remain unclear, but the operator of the Paris underground train service said his body was found between two carriages shortly before midnight.
While friends have denied he was train-surfing at the time, a French police source told AFP he "was trying to climb on to the roof of the metro when he fell. He suffered a severe head injury."
The parkour group said in a statement, however, that Newman was not riding a train in the accident.
"So some of you might have heard, one of our team members Nye Newman passed away today in Paris after a train accident on the metro," the group wrote on Facebook on Monday.
"He wasn't train surfing as many of you may assume, many of you may think it's a joke and we really wish it was, but it isn't."
Newman himself shared a picture on the day before New Year's Eve that appears to have been taken from the top of a Paris bridge above the Metro line (see below).
Many took to social media to share tributes about the young free runner.
"Nye was an incredible human being who was always up for anything, he experienced things in his short life, that many won't experience in their life times,” the Brewman group wrote.
"He was always up for anything, and he always gave a positive outlook to any situation. He was the type of guy who had no regrets in his life and lived everyday like it was his last."
Newman's last social media post came on the day of his accident, and showed an old image of what appear to be his own legs dangling over a building edge in Hong Kong.
"It's been a hectic year full of lots of mental memories and some unfortunate things like leaving the EU, but hopefully it will all only lead to a better future," he wrote.
Below is a December video of the free-running group on top of a Paris Metro.