The early 2000s were a magical era for action cartoons. Ask any twenty-something. Cartoon Network, Nickelodeon, and even Disney Channel used to air complex, engaging, impactful shows that got kids standing on their sofas. Teen Titans remains one of the best-remembered entries in the genre. Despite a recent crossover with its more comedic spin-off, the show ended triumphantly after five excellent seasons and a movie. Teen Titans still left one of its most notable mysteries willfully unanswered. Just who was Red X?