subreddits related to r/Pictures
Science Fiction, or Speculative Fiction if you prefer. Fantasy too. Asimov, Bradbury, Clarke, Dick, Heinlein and other SF books. SF movies and TV shows. Fantasy stuff like Tolkien and Game of Thrones. Laser guns, space ships, and time travel. etc. Star Trek, Battlestar, Star Wars, etc.
/r/photography is a place to discuss the tools, technique and culture of photography. This is not a good place to simply share cool photos or promote your work, but rather a place to discuss photography as an art and post things that would be of interest to other photographers.
/r/Zombies' raison de la mort is to host submissions regarding gatherings, movies, books, music, theater, speculative science, and games featuring the flesh (and/or brain) eating dead. Non-zombie "zombie" news (re: banks, computers) will be deleted. If you have doubts, or are just wondering whether your nascent question has been ridden into the ground already, check out our FAQ.