Icons

What makes an icon and icon? Like for instance, Judy Garland and Cher are gay icons, I think. i don't see why Judy Garland would be. She isn't masculine in any way shape or form. Is it the Dorothy thing and being accompanied down a yellow brick road by three men (are they really men though?). Becuase I see the whole innocent, farm girl braided hair, on the verge of adulthood thing kinda a stripper, Playboy layout fantasy wet dream thing. You know the whole is she a girl, is she a woman sort of thing is kinda sexy.
I love the show "Will and Grace" and the most flamboyant of the characters, Jack is always talking about Cher. There are even some episodes which have Jack carrying around a Cher doll. He even makes reservations and one restaurant with a seat intended for this Cher doll. And Cher is always one of the most used personas for drag.
I'm wondering why these celebrities are icons. Is it because they as persons have always accepted homosexual lifestyles as normal (I actually don't know their personal views) or just because of something they represented--Judy Garland for the "showtunes" which are always a red flag for homosexual!!! It always seems homosexuals are stereotyped as liking showtunes.
I'm just wondering what makes an icon and icon.