Paul Warfield, Larry Csonka, and Jim Kiick
Another attempted NFL rival, the woefully-misnamed World Football League lasted for two seasons and never actually had any teams from outside the United States. The league also struggled to keep teams afloat in a number of markets, with Detroit and Jacksonville folding before the end of the first season while New York and Houston both moving in the middle of the year. However, two WFL alumni (Larry Csonka and Paul Warfield) eventually wound up in the Hall of Fame. Like baseball's Federal League, the course of NFL history was changed when Csonka (and several other Miami Dolphins players) decided to switch leagues.
Many WFL franchises were former minor league teams, and the demise of the WFL essentially ended minor league football in this country. The league is also considered a pioneer in nicknaming, as a number of teams ("Fire", "Sun", "Bell", "Storm", "Steamer", "Thunder", "Express") were in the singular tense as opposed to plural.