Geek culture in the past was primarily thought of as comic books, sci-fi and role playing games. It really included anything that the "cool" kids weren't into. Comic books were the main public face when I was growing up. Dungeons and Dragons was another sure sign of geekhood. There were things like horror movies that many geeks were into, but so were a lot of other people so they didn't really fall into the category. Certain things like Monty Python did though, because the core audience tended to cross over more often than not. Back then, it was more about the type of person that the product appealed to than it was about the content of the product itself.
There have always been divisions in geek culture. Someone might be a comic book geek but they don't like Star Wars. Someone else might be really into epic fantasy but they think superheroes are lame. These days with the large expansion of geek culture this has been amplified. There has also been an expansion of what people think of as geek. Video games and anime were just starting to become popular when I was a kid, and anime especially was a very niche interest until recently. I remember telling people about Akira and Vampire Hunter D when I was a teenager and they would tell me they were not interested in watching some dumb Japanese cartoon.
Horror and supernatural suspense have also come under the geek umbrella. This is where the conversation that changed my thinking about geek culture came in. There was a discussion about whether Twilight was geek culture. I fell very solidly on the No side. People were very upset with me. Then someone asked since I didn't feel it was geek did I consider Harry Potter to be geek. I again said No and lynch mobs were raised. I was a little confused about why it was so important that these franchises be labelled as geek. Growing up we were always trying to convince our friends why Batman wasn't really that geeky, in hopes of spreading his appeal.
I also want to point out that just because I didn't consider something geeky, didn't mean I didn't like it. I really enjoyed the Harry Potter books and movies. Twilight was not my cup of tea, but growing up I read all of Anne Rice's vampire books, even though I never considered them to be geeky. Geek just had certain connotations to me that these things didn't fit. After everyone was done yelling at me via Facebook, I really thought about this. I have seen for a while that geek has been losing its stigma. That's part of the reason I started Geeking Out With Geekboyking. (I do want it noted however that I have been going by geekboyking on the interwebs for far longer than it has been cool to be a geek. In fact it has been so long that I sometimes wonder whether I can rightly call myself geekboyking instead of geekmiddleagedguyking.)
These days though,everyone likes superheroes, even if they don't read the comics. All kinds of people play table top games and video games. The Lord of the Rings went from being read by a few fantasy freaks and Led Zeppelin fans to being made into blockbuster movies. I also realized that there are things I associate with being a geek that others might not. Many might not think of heavy metal music as being geeky. In my mind though, the band Iron Maiden will forever be linked to marathon Dungeons and Dragons sessions. 80's hard rock and heavy metal very definitely have a spot in geek culture for me. And I thought back to something I have said many times. Everyone is a geek about something. I know lots of quotes and facts from Star Wars. My brother in law knows lots of facts and statistics about football. He would claim his is less geeky because football players are real people. But he has invested his time and energy into memorizing facts about people he has never met. That's geeky.
So, my new more inclusive definition of geek culture is anything that causes people to geek out. If it inspires a passionate fandom, it is geek. If people will dress in funny ways to show their appreciation, then it is geek. If there is a lot of merchandise available to buy related to it, it is geek. So congrats to the random Twilight fans who so railed against me. I still don't think Twilight is very good, but I am willing to concede that it is geeky. Luckily for you this no longer means you are going to get beaten up and have your lunch money taken.