Why is Peter Dinklage stuck playing characters defined by dwarfism?

There's a lot to unpack about “Three Billboards Outside Ebbing, Missouri,” Martin McDonagh's lacerating, highly inconsistent drama about Mildred (an outstanding Frances McDormand), a woman who begins to unravel and publicly calls out the local police chief (Woody Harrelson) after her daughter is raped and murdered and the investigation stalls.

But when I walked out of the theater after a press screening in October, my dominant feeling about the movie was one of rage, and not even about the film's most obvious targets for that emotion. Instead, it broke my heart to have watched yet another movie in which Peter Dinklage, who ought to be one of the breakout stars of this moment, ends up playing a character defined almost entirely by his dwarfism.

This is particularly infuriating because, since 2011, Dinklage has been one of the most important breakout characters in one of pop culture's most important phenomena, playing Tyrion Lannister in 61 episodes of HBO's “Game of Thrones.”

In both “Game of Thrones” and the George R.R. Martin novels on which the show is based, the discrimination Tyrion Lannister has faced because of his dwarfism has had a considerable impact on his life and his choices. But his dwarfism is not the sum of his life and his choices.

Tyrion is defined as much by his appetites for sex, food and drink, his fateful romantic streak, his strategic cunning, his curiosity about the world around him, his love for his brother Jaime (Nikolaj Coster-Waldau) and his inability to pass up an opportunity to tweak his sister Cersei (Lena Headey) as he is his stature. Tyrion's arc on the show, from his introduction as a wine-soaked patron of prostitutes, to our last glimpse of him as a morally tortured adviser to a young king and queen (Kit Harington and Emilia Clarke) is among the most important throughlines on “Game of Thrones.”

If Hollywood was an industry that looked at the evidence and made decisions based on it, “Game of Thrones” would have made Dinklage a major star. He appears in more episodes of the show than any other actor, including Harington and Clarke, who would be the unquestioned heroes of a more traditional fantasy story. And “Game of Thrones” has proved Dinklage can do it all: gut his way through a tense confrontation, throw a fit, be funny, be melancholy, be heartbroken, be sexy. A sane business would experiment with making him the lead in a smaller ensemble cast, would think about how to use him in an action sequence, would know that he can do a sex scene and have a sense of how to choreograph it.

But, as we know from many things, including the entertainment industry's persistent neglect of black and Latino audiences and its slowness to greenlight superhero movies with female leads, Hollywood is not the purely rational business it likes to make itself out to be. And Peter Dinklage is not the star he could be.

None of this is to say that Dinklage is bad in “Three Billboards Outside Ebbing, Missouri.” He's not. As James, who has a persistent and unrequited crush on Mildred, he's soulful and tart and inventive. The problem is, his character in the story is, once again, defined by his dwarfism.

James is introduced as “the town midget,” and that's how Mildred describes him when she explains that she thinks he's interested in her. Later in the movie, he provides an alibi for her in exchange for Mildred's promise to go on a date with him, an event that turns into a spectacle of humiliation when Mildred's ex-husband Charlie (John Hawkes) mocks her for being seen with James.

“I know I'm a dwarf who sells used cars and has a drinking problem, but who the (expletive) are you?” James asks Mildred bitterly toward the end of their evening. His apt diagnosis of Mildred's unwarranted superiority would sting a lot more sharply if “Three Billboards Outside Ebbing, Missouri” let James be more than his height and the town's reaction to it.

Hollywood's ability to squander Dinklage's talents isn't the worst or only tragedy of the industry's narrow-mindedness. But though I'm sure McDonagh didn't intend it, seeing Dinklage in one of these roles again, despite everything he has accomplished over the past seven years, is one of the most lacerating things about “Three Billboards Outside Ebbing, Missouri.”