Which retired kickboxer shares the record for world championship titles with Sem "Semmy" Schilt?
Semmy Schilt:  He is the only fighter in K-1 history to win the world championship three times in a row, and also shares the record with Ernesto Hoost for most Grand Prixs won, with four. Ernesto Hoost:  He announced his retirement on December 2, 2006 after the K-1 World GP Final tournament in Tokyo Dome, Japan.
Ernesto Hoost