Warner Bros, Heyday Films, and Patalex IV Productions Limited
Take a bow, Warner Bros, Heyday Films, and Patalex IV Productions Limited—without you, Harry Potter and the Goblet of Fire would have just stayed a little, unknown book (er, well, maybe not exactly "unknown"—but it's still nice that they made a movie).
You probably know Warner Brothers. Everyone knows Warner Brothers, because they've produced (and distributed) thousands of films since the mid-20th century. We won't try to list all of them, don't worry—even just listing the features that are upcoming for the next five years would be too long for this space.
However, just to give you a little taste, WB has put out movies such as Magic Mike (2012), Interstellar (2014), Gravity (2013), Argo (2012), Inception (2010), and, of course, all of the Harry Potter films.
Yeah—lots of different genres and subject matter on offer there. But that's WB's deal: they produce movies spanning the "Shirtless Channing Tatum Dancing" genre all the way to the "Big-Eyed Reluctant Wizard Hero Winning Tournaments" genre.
Heyday Films is pretty different from WB. The most major difference: its list of films isn't as long as the King James Bible. Even so, they also produced all the Harry Potter films. Guess if you've got a winning formula, you keep the production team together, right?
Their resume is probably heavier on the kids-friendly fare, percentage wise. Like, in addition to the Harry Potter films, they've done Paddington (2014; with sequels planned) and Fantastic Beasts and Where to Find Them (2016) (yup, another J. K. Rowling special).
Of course, they also did The Boy in the Striped Pyjamas (2008), which is about the Holocaust, and the first film listed on their IMDb page is Ravenous (1999), which is supposedly about a "rescue mission which takes a dark turn when they are ambushed by a sadistic cannibal." So, clearly Heydey is pretty comfortable with the darker material too.
Patalex IV Productions literally has one credit listed: this one. So, not too much to tell you about that one. Maybe Warner Brothers can lend them a couple of movies to put on their resume?