I'm on a website called Tumblr, and want to put out "Tumblr: The Unofficial Album" with musical parodies I've written of the content in that site, which is actually content from TV shows, books, movies, etc. For example, there's a song titled "A Doomsday Love Story", which is about the Rose/Doctor pairing in Doctor Who, set to the music of Taylor Swift's "Love Story". All the songs are parodies, but none of them really have much to do with the songs they're set to. Is it legal for me to do this? If maybe I added a sort of disclaimer saying I don't own the songs or the works I'm singing about? If so, what would I have to put in that disclaimer? Or would I have to get explicit permission from the creators of both works? Or a license? Thank you for your advice.