Voting has concluded in this first-round matchup, but check out the results of all the matchups in ESPN.com's Action Sports Star bracket.
Here's the final tally in this matchup: Kelly Slater: 1,461 votes; Robbie Maddison: 598 votes.
Kelly Slater
Age: 40
Country: United States
Sport: Surfing
Credits: Slater has won a record 11 ASP world titles and is the all-time leader in event victories.
Robbie Maddison
Age: 30
Country: Australia
Sports: Motocross, rally car racing
Credits: "Maddo" won a silver medal in Best Trick at the 2010 X Games but is best known for his daredevil stunts, such as jumping 96 feet up onto a replica of the Arc de Triomphe in Las Vegas and jumping London's Tower Bridge with a backflip.
Click here to view results in the next matchup, Shaun White versus Ken Block.