In honor of their great players, teams retire their numbers. But if that player has been one of the all time greats, then the league might consider retiring that number. As an example, Wayne Gretzky's number 99 has been retired across the NHL.
Is this the only example where a number is retired in an entire league? If not, please provide the player's name and number, as well as the teams he played for.
I'm looking for an answer for major leagues (i.e. MLB, NFL, NBA & NHL). But if there happens to be no retired numbers, then we can take a look at soccer leagues such as the EPL, LaLiga and Bundesliga.