This is one I've had on my radar for a long time but didn't have enough proof to include...until now.
The Narrows were first introduced in Batman Begins (2005). They were the slums of Gotham, the worst part of an all-around bad city, and they were where most of the action of the movie happened. By the end of the movie, the Narrows was in rough shape, having been overtaken by escaped Arkham inmates, much of their infrastructure destroyed by the microwave emitter, and engulfed in weaponized fear toxin.
As far as I can tell, the Narrows made their comics debut in Batman: The Dark Knight #2 (October 2011) during a montage of Gotham areas being attacked by escaped Arkham inmates. Canon immigrants like locations and costumes are a lot harder to trace than characters, so this may not be the actual first appearance - and if it's not, please let me know what is. But it is at the very least an appearance, which is good enough to show that it is indeed in the comics.