One of the most persistent and unkillable myths in the history of comics is the “saving” of Batman by Frank Miller. You’ve probably heard it. The Batman comics were just a giggling campy mess after the sixties TV show and it was only with Frank Miller’s seminal The Dark Knight Returns in 1986 that Batman became dark and gritty again. Cool story, but complete guano (and one I’m pretty sure I helped spread at a much earlier point in my career as a semi-professional nerd rodent). Truth is, the comics had been pushing back hard against the BIF BAM KAPOW image from as early as 1970 in an attempt to bring Batman back to his roots as a grim, brooding nocturnal hero.
What The Dark Knight Returns did do was bring that darker Batman that was already present in the comics to a much wider audience. DKR was published in 1986, the year that also saw the release of Watchmen, and the release of these two comics in the still relatively new graphic novel format made about as big an impact as it is possible for comics to make.
Batman was the first attempt to reframe Batman in the popular consciousness from the Adam West incarnation into something closer to his comic depictions. Did it succeed?

“Yeah. Yeah, just a bit.”
To put it another way, this is by far the single most influential depiction of Batman in any medium in the eighty year history of the character. This movie was where Batman went from “Flagship comic book character and star of a pretty popular TV show” to “Modern Secular God”. In terms of box office, merchandising revenue and pop culture impact it was on the Star Wars tier. “Fine Mouse”, you say. “But what’s it done for us lately? Does it stand up?”
To which I say, “Yes. It does stand up. And then it flaps its wings, like a pretty, pretty butterfly.”