someone who is dedicated to something even much more so than a hardcore fan If it is a musician that is a different gender than the fan, they will open the window whenever the musician/band's music plays because they think the musician/band member is hot. If it's an actor or actress, then they will own every movie or television show the actor/actress stars in and watch every episode or movie the day it comes out. If it's an athlete, then the definitions that have defined superfan will apply. If it's a politician or radio personality, then they will listen to said politician/radio personality's shows every day.
Brad: "I don't understand why Karen opens the window whenever Nickelback's songs come on the radio. They're not as great as she says they are. She does it in the middle of winter, and I had to tell her to close it because I was cold".
Jason: "Karen's a superfan, Brad. She thinks Chad Kroeger, the singer, is hot, although I've heard nothing but negativity about him".