Jake Gyllenhaal has spent much of his career refusing to become easy to define.

He has played a teenager haunted by visions, a Wyoming cowboy trapped by the limits of his time, an obsessive cartoonist hunting a killer, a relentless detective searching for missing children and, perhaps most memorably, a frighteningly ambitious cameraman prowling Los Angeles after dark.

That willingness to move between blockbusters, intimate dramas and unsettling psychological thrillers has given Gyllenhaal one of the most varied filmographies of his generation.

These 10 movies represent some of his strongest performances and the films that did the most to shape his career.

10. October Sky — 1999

Before the darker roles that would eventually define much of his career, Gyllenhaal starred as Homer Hickam in October Sky, the story of a West Virginia teenager inspired by the launch of Sputnik to experiment with building rockets.

The film gave the young actor an opportunity to carry an emotional coming-of-age story built around ambition, family expectations and the desire to imagine a future beyond the life already planned for him.

Gyllenhaal was still years away from international stardom, but October Sky demonstrated the sincerity and vulnerability that would remain important parts of his screen presence.

9. Source Code — 2011

Source Code proved that an intelligent science-fiction movie did not need a sprawling running time to create a complicated idea.

Gyllenhaal plays Army pilot Colter Stevens, who repeatedly experiences the final eight minutes aboard a Chicago commuter train while trying to identify the person responsible for an explosion.

Each return gives him another opportunity to understand what happened — and gradually forces him to question the reality of his own situation.

The movie moves like an action thriller, but Gyllenhaal keeps its increasingly emotional questions grounded.

8. End of Watch — 2012

Gyllenhaal and Michael Peña provide the heart of David Ayer’s End of Watch.

They play LAPD officers Brian Taylor and Mike Zavala, partners whose dangerous patrol work is balanced by the friendship and everyday lives they share away from the job.

When an investigation draws them into conflict with a criminal organization, the movie becomes increasingly tense, but its impact depends heavily on the believable bond between the two leads. The BFI praised both actors’ performances when the film competed at the 2012 London Film Festival.

For Gyllenhaal, it was another reminder that physical intensity works best when audiences care about the person underneath it.

7. Enemy — 2013

Few Gyllenhaal movies are as strange as Enemy.

Directed by Denis Villeneuve and adapted from José Saramago’s novel The Double, the psychological thriller casts Gyllenhaal in two roles: Adam, a withdrawn professor, and Anthony, an actor who looks exactly like him.

Their discovery of each other creates an increasingly unsettling story about identity, desire and control.

Rather than distinguishing the characters through obvious tricks, Gyllenhaal changes posture, confidence and emotional energy. The result helped establish the productive creative connection between him and Villeneuve.

6. Nocturnal Animals — 2016

Tom Ford’s Nocturnal Animals asks Gyllenhaal to operate inside two interconnected realities.

Amy Adams plays Susan, an art gallery owner who receives a manuscript from her former husband, Edward. Gyllenhaal plays Edward in Susan’s memories and Tony, the central character inside the disturbing novel she begins reading.

The structure allows him to explore different versions of fear, weakness, anger and regret while the movie gradually reveals why the manuscript affects Susan so deeply.

His work earned him a BAFTA nomination for Leading Actor.

5. Donnie Darko — 2001

A giant rabbit named Frank tells a troubled teenager that the world will end in 28 days.

That premise helped turn Richard Kelly’s Donnie Darko into one of the defining cult films of the early 2000s — and transformed Gyllenhaal into an actor worth watching closely.

As Donnie, he balances teenage anger, vulnerability, humor and growing fear while the story moves through suburban life, visions and questions about time and fate. The BFI later described the film as a cult favorite and praised the nuance of Gyllenhaal’s performance.

The film remains one of the roles most closely associated with the beginning of his adult career.

4. Zodiac — 2007

David Fincher’s Zodiac is less interested in giving audiences an easy murder mystery than in showing what an unanswered mystery can do to the people trying to solve it.

Gyllenhaal plays Robert Graysmith, the San Francisco Chronicle cartoonist who becomes increasingly consumed by the hunt for the unidentified Zodiac killer.

Alongside Robert Downey Jr. and Mark Ruffalo, Gyllenhaal helps turn the investigation into a study of obsession. Years pass, leads disappear and certainty remains frustratingly out of reach.

His quiet transformation from curious observer to consumed investigator is one of the film’s strongest elements.

3. Brokeback Mountain — 2005

Gyllenhaal’s performance as Jack Twist marked a major turning point.

Ang Lee’s Brokeback Mountain follows Jack and Ennis Del Mar, played by Heath Ledger, after the two men meet while working in Wyoming in 1963 and begin a relationship that continues across years of separation, marriages and social pressure.

Gyllenhaal gives Jack an openness that contrasts with Ennis’ emotional restraint. Jack keeps imagining that their relationship might become something more permanent, making his hope increasingly painful as the years pass.

The role brought Gyllenhaal his first Academy Award nomination, for Supporting Actor, and he won the BAFTA in the same category.

It remains one of the most important performances of his career.

2. Prisoners — 2013

In Prisoners, Gyllenhaal reunited with Denis Villeneuve for one of the darkest crime thrillers of the 2010s.

Hugh Jackman plays Keller Dover, a father whose daughter disappears along with her friend. As Dover becomes increasingly willing to cross moral and legal boundaries in his search for answers, Detective Loki, played by Gyllenhaal, pursues the case through official channels.

Loki is a fascinatingly restrained character. Gyllenhaal gives him nervous habits, controlled frustration and a sense that his mind is constantly working even when he says very little.

Surrounded by desperation and suspicion, he becomes the movie’s determined center.

1. Nightcrawler — 2014

If one performance best explains why Jake Gyllenhaal became such a compelling actor, it is Lou Bloom.

In Dan Gilroy’s Nightcrawler, Lou discovers that graphic footage of crime scenes and accidents can be sold to television news stations. He begins roaming Los Angeles at night with a camera, gradually learning exactly how far he can push situations to obtain more valuable images.

Gyllenhaal makes Lou unnervingly polite, relentlessly ambitious and almost completely detached from ordinary morality. The movie uses his rise to examine the uncomfortable relationship between sensational television news, violence and the audience willing to watch it.

The performance earned Gyllenhaal a BAFTA nomination for Leading Actor.

More importantly, Lou Bloom became the kind of character that is difficult to separate from the actor who created him.

That may be the clearest thread running through Gyllenhaal’s best work. Whether he is playing Jack Twist, Robert Graysmith, Detective Loki or Lou Bloom, he rarely seems interested in making characters simply likable.

He makes them specific.

From Donnie Darko to Nightcrawler, his strongest films repeatedly place him inside people driven by obsession, fear, love or the desperate need to understand something they cannot easily control. More than three decades into his screen career, that unpredictability remains one of the biggest reasons audiences still do not quite know what a Jake Gyllenhaal movie will look like until he appears on screen.