For as long as there have been works, there have been fanworks – works made by people who feel so passionately about something that they want to discuss it, make new things about it, and join with others who feel similarly about it. Fanworks are often described in the Internet age as kinds of “user-generated content.” Because anyone can make them, share them, and experience them, fanworks provide uncommonly powerful opportunities for expressive empowerment, access, and inclusion. In addition, fanworks are uniquely well suited to advancing social justice by using well-known sources to highlight injustices; and the affinity groups that surround fanworks carry special potential to empower creators and act as sites of progress. At the same time, fanworks have a tense relationship with intellectual property (IP) doctrine and enforcement: fanwork creators are authors in their own rights, but because fanworks build upon pre-existing material, they can also run afoul of actual, perceived, or threatened copyright and trademark risks. This chapter addresses those potentials and precarities. It explores the relationship between fanworks, social justice, and law to highlight how, by providing avenues for access, inclusion, and empowerment, IP doctrines that encourage fan endeavors also advance the goals of IP social justice (IP-SJ).