12 Mike Tyson
11 Sonny Liston
10 Lennox Lewis
9 Jim Jefferies
8 Jack Dempsey
7 Rocky Marciano
6 Evander Holyfield
5 Larry Holmes
4 Jack Johnson
3 George Foreman
2 Joe Louis
1 Muhammad Ali

I know the title calls for 10, but IMO you need 12 to get Tyson on there.