There are many threats in Fantastic Beasts and Where to Find Them. Not only does Newt Scamander have to run around 1926 New York City to collect his many magical beasts, he also stumbles upon a dark threat in the American wizarding world and, on top of all of that, the entire wizarding community is dealing with the ominous threat of Grindelwald. Many beasts have been teased in trailers, photos have been released, but one supposed beast that has been kept top secret is the Obscurus. Fans picked up on this name when Pottermore unveiled the official soundtrack, and it's clear that the Obscurus in Fantastic Beasts and Where to Find Them has a major impact on the story.
Going off its name alone, the Obscurus doesn't sound like the kind of "fantastic beast" you want to cuddle. The word "Obscurus" indicates something dark and ominous (something obscure), and the original assumption around the web was that the Obscurus is the ultimate beast that threatens the entire city. Inverse theorized that the Obscurus was the large monster barreling through NYC in the early trailers, or that it was the dark smoke that appears to be chasing Newt under ground in a subway station. And in the actual movie, the Obscurus (spoiler alert!) turns out to be just that, but also much more.
Part of the reason fans didn't know anything about the Obscurus beforehand is that it's never once mentioned in Newt's textbook, Fantastic Beasts and Where to Find Them. And its absence certainly begs the question: is the Obscurus even a beast at all? Not quite. It causes danger, yes, but is actually a form taken by a human wizard who's repressing his or her powers. The Obscurus is actually a dark magical force that causes real harm, and it is, essentially, the physical manifestation of a wizard's magic. So, a wizard, say, who didn't get to study at school or has tried to keep his powers hidden from the outside world could create a very dark and very powerful Obscurus.
Interestingly enough, Newt's original Fantastic Beasts book was published by a company called Obscurus Books. Right now, this is just a fun piece of trivia, but I'm willing to bet it will come back in future films, even if the Obscurus doesn't.
Images: Warner Bros Pictures; fantasticbeasts/tumblr (2)