All images and other two-dimensional works of art, as well as music files, are most likely owned by either the artists who produced them, the people who commissioned the works, or the heirs thereof. It is believed that the use of low-resolution images of works of art and low-quality sound files on our English-language, parody, non-profit website with educational purposes qualifies as fair use under United States copyright law.
Any other uses of these works might be copyright infringement.