Made for each other
A funny fantasy fanvid with Viggo Mortensen and Stephen Colbert
US Copyright Office: Derivative Works wrote:
A "derivative work," that is, a work that is based on (or derived from) one or more already existing works, is copyrightable if it includes what the copyright law calls an "original work of authorship." Derivative works, also known as "new versions," include such works as translations, musical arrangements, dramatizations, fictionalizations, art reproductions, and condensations. Any work in which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship is a derivative work or new version.