Ken Shamrock (10-1)
Good story, terrible fight. Shamrock may be so scorched that he probably can't shoot a takedown, which would mean Royce would try to drag him down in his guard. But Shamrock allegedly owes Zuffa court fees over a contract dispute, and this would be one way of working it off. (Biggest obstacle: Gracie would have to drink a ton of water to weigh in at the minimum 186 pounds for a fight at 205.) Maybe more appropriate for the 20th anniversary of the UFC in 2013, but that assumes Shamrock isn't in traction by then.
Kazushi Sakuraba (12-1)
He split two fights with Gracie, including a 2000 bout that, at 90 minutes, was "The Godfather" of MMA matches. Getting him would require negotiating with Dream/Japan, and although that's not impossible, it's probably not worth the hassle.
Matt Hughes (20-1)
Dearly beloved, we are gathered here today ...
James Toney (60-1)
Classic matchup -- and one the Gracies always wanted -- but the UFC won't deviate from state commission standards, even though Brazil is a pretty liberal place for a fight.
Roy Jones Jr. (100-1)
Right weight class, and Jones was willing to fight Anderson Silva under MMA rules. But expensive.
Yoshihiro Akiyama (10-1)
Akiyama originally was supposed to fight Gracie in Japan several years ago but he injured himself. He would probably keep Royce standing and pummel. Depressing.
Wallid Ismail (3-1)
Ismail never got much momentum going as an MMA fighter and hasn't fought in eight years. But he did choke out Gracie in a jiu-jitsu bout in Brazil in 1998, the first real indication the guy was human. Bonus for promotion: In the arena of trash-talking, Ismail is the Brazilian Chael Sonnen.
Source: ESPN