Often cited as one of Joss Whedon's finest hours of television (aside from the Buffy episode "The Body", but that's far less sad than it is heartbreakingly sad), "Objects In Space" serves as both Firefly's final episode and the introduction of one Jubal Early, the strangest and most philosophical space assassin in history. "Am I a lion? I don't think so. I do have a mighty roar." That's just a taste of Early's brand of whimsical misunderstandings as he invades Serenity and holds members of the crew hostage while attempting to trap down resident fugitive River Tam. Failing to track her down and threatening to kill River's brother Simon, Jubal finds himself forcing the residents of the ship to face up to their own limitations before starting a conversation with Serenity itself. It's not long before he realises his mistake and is summarily kicked off, but the questions posed during his time aboard Mal's ship are potent enough that you'll be scratching your head thinking about them for long after the episode's over.