1. In the early 1990s, current Denver Nuggets NBA star Allen Iverson played myriad positions for Bethel High School's football team in Hampton, Virginia. According to a local newspaper at the time, "Iverson the quarterback passed for 1,423 yards with 14 touchdowns. Iverson the runner gained 781 yards with 15 touchdowns. Iverson the kick returner scored five touchdowns, four on punts. Iverson the defensive back intercepted eight passes."
Here's Iverson's highlight reel:
2. The only major league baseball player to have won a Gold Glove as both an infielder and an outfielder, Darin Erstad, was also the starting punter on the Nebraska Cornhuskers football team in 1994 and helped the team win the national championship.
3. Cleveland Cavaliers star LeBron James attended St. Vincent - St. Mary High School in Akron, Ohio where he made First-Team All-State as a wide receiver in 2001. A mere three years later, he was named NBA Rookie of the Year.
4. While we all know about Jackie Robinson's Brooklyn Dodgers debut in 1947, ending eighty years of baseball segregation, few are aware that Jackie also played basketball, tennis, track and field and was quite the quarterback for John Muir High School in Pasadena, CA.
Of course, there are many more professionals sports figures who played high school and/or college football before settling into another sport. Marlon Byrd, to name another. Why don't we get a nice list going in the comments. Show off your smarts time!