The final factor requires a court to consider not only the harm to the market caused by the allegedly infringing use, but also the potential for harm caused by others following in the alleged infringer's footsteps, as well as any harm to the market for derivative works. (concluding that a trivia book based on the popular television show Seinfeld could harm the market for similar derivative products produced or licensed by the copyright owner). Works that purport to be an homage to the copyrighted work may nevertheless weaken the market for licensed derivative works.