Season 4, episode 19
Writers: Akiva Goldsman, J.H. Wyman, Jeff Pinkner
Director: Joe Chappelle

What at first seemed to be one of Fringe's nutty number 19s turned out to be the episode that helped earn the series a fifth and final year. Of course, some may now question the merits of ringing out the series with a season-long story set entirely in this future dystopia ruled by oppressive Observers. But the single episode that introduced this premise was a cool jolt that opened a new front of Fringe mythology and gave us a character that would have a lasting impact, Etta (Georgina Haig), the adult daughter of Peter and Olivia.