Joi Harris, known as SJ, was killed when her motorbike went out of control and she was thrown through a glass window in a building in downtown Vancouver, Canada.
Making the tragedy even more sad is reading on Facebook that Joi had posted a photo of herself only three days before the incident with with a cryptic caption.
The film's star Ryan Reynolds, who was born in Vancouver, tweeted in the wake of the incident on Monday, August 14.
Witnesses said Ms. Harris, who was working on her first movie, had been riding the bike down a set of stairs when she lost control, jumped a curb and crashed into the Shaw Tower.
"People were running on the sidewalk, the motorcycle comes flying across the street, looks like from a ramp because it was in the air. The rider was standing on the bike, slams into that building, clearly hit and out of control and clearly not planned," said one eyewitness.
She was rushed to hospital but was dead on arrival.
Deadpool's co-creator paid tribute to her on social media.
Condolences to family, friends and co-workers of Joi “SJ” Harris who lost her life today while making movie magic for all of us. #Deadpool2— Fabian Nicieza (@FabianNicieza) 15 August 2017
Her crumpled motorcycle lay on the sidewalk as actors and camera crew, many of them in tears, gathered around.
Ms. Harris was the stunt double for actress Zazie Beetz, whose character, Domino, is a sexy mutant mercenary who teams up with Reynolds' character, Deadpool, a wisecracking bionic superhero.
She was not wearing a helmet but is believed to have been wearing an afro wig, to make her look like Beetz.
Ms. Harris, who was from New York, was an expert motorcyclist and the first African-American woman in US history to compete in a sanctioned road racing event.
On her website she posted her motto for life.
"One life, one chance, 24 million possibilities, hold your line" — SJ.
Holding your line, in motorcycling jargon, is a way of maneuvering around a corner without coming off the bike.
"We are deeply saddened by the accident that occurred on the set of Deadpool 2," said a statement from filmmakers Fox.
"Our hearts and prayers are with the family, friends and colleagues of our crew member during this difficult time," it added.
Ms. Harris joined an elite group of black stuntwomen — Fay Le Baker, Jadie David and Kym Washington — who had worked in Hollywood.
Washington was probably the most prolific, having been a stunt double for Whoopi Goldberg, Queen Latifah, Halle Berry and Angela Bassett.
Last month another Hollywood movie claimed a life. Stuntman John Bernecker died after falling 25 feet from a balcony, narrowly missing a safety cushion, while filming the US TV series The Walking Dead.
Over the years dozens of actors and stuntmen have been killed making movies.
One of the most famous incidents was in 1993 when Brandon Lee, the son of martial arts legend Bruce Lee, died on the set of The Crow when he was shot with a gun which was supposed to be firing blanks.