The X-Files: 10 Original Series Characters Who Should Return

10. William

Appeared In: Seasons 8 & 9. Last Seen: Having his biology normalized by Jeffrey Spender in an attempt to thwart the alien colonization, before he was given up for adoption off-screen in the ninth season's final stretch of episodes. Why He Should Return: Though baby William was written off the series, his impact has continued to be felt through Scully and Mulder, both in 2008's I Want to Believe film and throughout Season 10's entire run. Both characters even imagined their lives with him in the episode Founder's Mutation, and their regret about having given him up has only grown stronger. Considering how much he was played up in the latest season, it'd be no surprise if he does indeed make a comeback sooner or later, and there would undoubtedly be a wealth of dramatic material inherent in reuniting our favorite agents with their long-lost son.