Lots of actors have played famous authors in movies, but Nicholas Hoult does them one better. After taking on J.D. Salinger in “Rebel in the Rye,” he now turns to J.R.R. Tolkien in Dome Karukoski’s “unauthorized” take on the philologist/writer who created the fantasy world of hobbits that has entranced so many devoted followers. Hoult is quite good in both parts; unfortunately, the movies are overall disappointments.

“Tolkien” takes up the writer’s life when he was an adolescent (Harry Gilby), gamboling about with friends in the English countryside. His father had died some years earlier, but he’s happy with his mother (Laura Donnelly), who regales him and his younger brother with fantasy stories. Unfortunately, she finds herself in such financial distress that she’s compelled to move the family to a dingy flat in industrial Birmingham. (The script doesn’t bother informing us that their poverty resulted from the fact that she had converted to Catholicism, and her furious family cut off any further monetary help.)

Then she dies, and the priest whom she had appointed her sons’ guardian, Francis Morgan (Colm Meaney) places them in the home of wealthy dowager Mrs. Faulkner (Pam Ferris), who takes in orphans. He also secures the boys a slot at a posh prep school in the city, where Tolkien falls in with three other precocious classmates with whom he will form a de facto literary society. They’re Robert Gilson (Albie Marber), the son of the harsh headmaster (Owen Teale); Christopher Wiseman (Ty Tennant), a jocular sort; and Geoffrey Smith (Adam Bregman), an aspiring poet.

As Hoult takes over from Gilby, these three grow into Patrick Gibson, Tom Glynne-Carney and Anthony Boyle. They are the inseparable members of what at one point is called a fellowship, which, the film implies, was the model for the one in Tolkien’s later work—a group of comrades-in-arms in a fantasy world of threats and monsters drawn from what the writer, suffering from fever, experienced during his service at the Battle of the Somme in World War I, where two of his closest friends died. (Periodically surreal inserts of Tolkien’s frightful time in No Man’s Land as he desperately searched for them are inserted into the film. It’s hardly an accident that the lieutenant played by Craig Roberts who cares for Tolkien during his illness is named Sam.)

Another person Tolkien meets who contributes part of the world he eventually creates is Edith Bratt (played first by Mimi Keene, and then Lily Collins), whom, in this telling, he meets as another orphan in Mrs. Faulkner’s care. They grow close, and Tolkien comes to share her love of Wagner’s “Ring des Nibelungen”; though he can’t afford to take her to an actual performance, the two do get a chance to listen from the cellar of the concert hall, even miming the roles in a sort of early cosplay. But when Father Morgan comes to fear that their romance is interfering with Tolkien’s college-entrance exams, he orders the lad to cut it off—which his ward does, at least until he turns twenty-one.

Thus we get a foreshadowing of both the fellowship and the ring from the author’s youthful life, molded into something more imaginative by his experiences in wartime. Or so the film suggests.

How much of this is speculative and how much an actual reflection of Tolkien’s makeup is hard to assess (certainly his romance with Bratt is highly embellished), but the matter of Tolkien’s years at Oxford is based substantially on what actually occurred. He switched from classics to philology and become a pupil of Joseph Wright, the expert on Gothic, who apparently encouraged his fascination with imaginary language and Germanic myth. Then came the heroic struggles of the war and the painful loss of his friends.

As screenwriters David Gleeson and Stephen Beresford would have it, all these varied elements coalesced when Tolkien, having come back from the war and settled into academia and married life with Edith, whom he had never stopped loving (nor she him), sat down to write. The film ends with his composition of the initial sentences in a careful calligraphic hand and his invention of the term he would apply to his diminutive hero Bilbo Baggins; the concluding shot can be converted into almost Biblical terms: “And then there was…Hobbit.”

Tolkien himself would probably have objected to this neat cataloguing of influences as the explanation for his creative accomplishment, and his estate has pointedly disavowed the film; one certainly cannot deny that it takes liberties with the record. For one more interested in drama than biographical accuracy, however, the problem with “Tolkien” isn’t that it often plays rather loose with facts (in fact, it offends no more often than most movies based on the lives of real people) or that its psychological portrait of Tolkien is debatable (no such depiction can be taken as definitive). The difficulty isn’t so much that the picture is rather crudely reductionist, but that it’s stately, ponderous, and rather dull.

That’s not the fault of Hoult, who nicely conveys Tolkien’s naturally shy and nervous personality (Gilby captures that quality in the younger version of him as well), nor of the rest of the cast—Collins is quite lovely and engaging as Edith, however much the writers might have re-imagined her, and the younger and older actors who play his school chums are all effective, even if they sometimes overplay their characters’ ebullience and self-assurance (or, in later stages, their moroseness).

Nonetheless none of them, to a certain extent, can escape a certain feeling of archness that the staid, Masterpiece Theatre approach Karukoski imposes throughout. Though beautifully appointed—one has to admire the elegant period detail in Grant Montgomery’s production design and Colleen Ketsall’s costumes, and the luminous widescreen images cinematographer Lasse Frank has fashioned—Karukoski’s leaden pacing, even in scenes where the boys are at their most exuberant, and Harri Ylonen’s prosaic editing stifle the forward momentum. One can also question the wisdom (and quality of execution) in the recurrent World War I sequences, which are of course meant to be hellishly horrific but, with their mediocre special effects (including a few fantastic monsters), come across as a misjudged attempt to approximate a fever dream.

The film is enlivened from time to time by the work of veteran actors who know how to savor the opportunities for broadness the script provides. Meaney and Ferris are the most obvious scene-stealers in the initial stages, but the most notable example comes later, when Derek Jacobi shows up all too briefly as Wright, turning the old fellow into a wild-eyed, fanatical academic prima donna—the very image of a dotty Oxford don. It’s terribly hammy, but makes the movie’s pulse race for a change.

Scholarship on Tolkien has become a cottage industry, and legions of readers still flock to his books, and to the epic movies Peter Jackson has made from them. It’s doubtful that similar numbers will embrace “Tolkien.” Serious and reverential but stolid and oddly pedestrian, it will probably please the author’s devotees no more than those who have never opened one of his tomes.