Prior to becoming a star in professional wrestling, Ahmed Johnson, whose real name is Anthony Norris, played middle linebacker for the Dallas Cowboys for two seasons (1990 and 1991). He wasn't a big star, nor did he receive a lot of playing time, so he's not remembered by too many NFL fans.
In order to sell his big match at Wrestlemania 3 against Hulk Hogan, Andre the Giant was promoted as having an undefeated streak that stretched over fifteen years. Gorilla Monsoon heavily sold that fact as well. However, he had actually been beaten a few times in other countries during that time period.