Transformative works are creative works which are made by transforming or remixing other creative works. The term comes from US copyright law, where the test for Fair use includes the question of whether a work is "transformative". The term is similar in meaning to Remix.
Gendered aspects of remix vs transformative works
The term Remix culture usually denotes a majority-male creative subculture. Documentaries, blogs, and articles about remix culture usually focus on male practitioners and on genres of work which are most commonly done by men -- for instance, fan trailers and musical mashups -- while ignoring those more commonly done by women, such as fan fiction.
The Organization for Transformative Works is a majority-women organization which has popularised the term "transformative works" and, while intending to support all such works, to date has mostly focused on the majority-female subgenres of Fan fiction and Fanvids.