In 1995, ESPN introduced the X Games, thrusting young athletes involved in nontraditional sports past their cult followings and into the mainstream.
The inaugural event, staged in Newport, R.I., featured BMX racing and skateboarding, along with more obscure activities such as bungee jumping and sky surfing.
Since then, the X Games has evolved from its renegade beginnings to gain prestige as the world's biggest action sports extravaganza.
Once confined to an annual summer event in the United States, the X Games has spawned extremes of its own. There are now summer and winter events, much like the Olympics.
And it has gone international, staging competitions in Asia, Brazil, Dubai and Mexico.
Starting Thursday, the X Games will celebrate its 15th anniversary with a summer showcase in Los Angeles.
Here are some memorable moments from athletes who have tested the limits of gravity and become the new stars of stunts.
Tony Hawk's '900'
The most recognizable skateboarder anywhere, Hawk is a five-time X Games gold medalist. But his biggest moment came in 1999 when he pulled off the sport's first 900 spin (21/2 rotations above the halfpipe) during the best trick competition. That move helped garner Hawk and the Games wide appeal. Hawk now has a portfolio worth more than $250 million. This year, Hawk, 41, is returning as a television analyst for the Games.
Ryan Sheckler's perfect run
By the start of this decade, many of the X Games' established stars were well outside their youth culture that defined their sport.
With aging stars limping into the sunset, X Games organizers were searching for a youngster who could bring new life into their sports.
In 2003, Sheckler became the first skateboarder to land every trick in street skateboarding. He has since become a television star with his MTV reality show, Life of Ryan.
Travis Pestrana's double backflip
Pastrana took one last breath before cranking the throttle on his motorcycle and rocketing down the ramp.
Then he soared like an angel, backflipping along the way.
Not once, but twice.
Pastrana, a motocross superstar known for pushing the limits in his sport, upped the ante by pulling off the first double backflip to win the Moto X title at the 2006 X Games.
Pastrana has not tried the trick since. Now, he concentrates on Rally Car Racing, in which he won gold at the 2007 X Games.
Jake Brown's fall
Skateboarders who wow crowds in the Big Air event are always trying to test new heights. Most have a masochistic willingness to fall, again and again, in pursuit of the perfect trick. And the possibility of physical harm is very real.
In 2007, Brown had one of the most frightening body-meets-pavement experiences when he lost control while attempting a trick and fell the equivalent of four stories.
The impact of his landing was so severe that his shoes exploded off his feet. After laying unconscious for a few moments, he walked off on his own.
Brown spent three days in a hospital recovering from injuries that included a bleeding liver and a cracked vertebrae.
He came back in time to compete in last year's big air event, finishing third.