An Eagle Fan is a sports fan who roots for one or all of the teams whose mascot/emblem is an eagle. Teams include the Philadelphia Eagles and the Boston College Eagles.

A Philadelphia Eagles fan knows the proper way to sing the Eagles fight song. After touchdowns, sing at the top of your lungs

Fly, Eagles, Fly, on the road to vic-tor-y.
Fly, Eagles, Fly, score a touch-down 1-2-3.
Hit 'em low, hit 'em high,
and then watch our Eagles fly!
Fly, Eagles, Fly, on the road to vic-tor-y!
E! A! G! L! E! S! Eagles!

If you watch/listen to a Philadelphia Eagles game on the television or radio or internet you will hear the crowd at Veteran's Stadium doing the Eagles cheer.

"We had a pretty good following wherever we went and we had that in New York and Washington. It was different in Philadelphia. It's a different type of fan here. The other places are difficult as well, but here the fans are real blue-collar and tough. I enjoyed the fans' passion for the game. There were a lot of places we played where I would say the teams did not enjoy the home field advantage. Here, there was and is a definite home-field advantage."
-Troy Aikman on Philadelphia Eagles fans

See also Philly fan.