A
die-hard fan is somebody who is completely 100% obsessed with their favorite game, band, movie, etc. these
people wait in long lines, in the blistering
cold, just to bring home the new "thing" they are fans of.
Look at
Matthew, over there. He's been waiting
outside GameStop for 3 weeks, just to get the new Kingdom Hearts. He's such a savage
die-hard fan.