No doubt Phelps 8 gold in one Olympics is an incredable feat but I'm not sure about Michael being called greatest athlete ever. There are to many others from time gone by that could be worthy of the title "Greatest Ever". Worthy of consideration, Babe Didrikson (all around), Jesse Owens (runner), Al Oerter (Discus), Jim Thorpe (all around), Pele (Soccer), Muhammad Ali (boxer) and countless others. IMO each can only be measured from the era that he/she performed in. We all have our favorites and they are all Champions.