- “The saga of friendship comes an epic conclusion.”
How to Train Your Dragon: The Hidden World (also known as How to Train Your Dragon 3) is a 2019 computer-animated action fantasy drama film that is DreamWorks Animation's 36th feature film, loosely based on the book series of the same name by Cressida Cowell, produced by DreamWorks Animation with Dentsu and Fuji Television, and distributed by Universal Pictures. It is the sequel to How to Train Your Dragon 2 (2014) and the third and final installment in the How to Train Your Dragon film trilogy as well as the franchise. Written and directed by Dean DeBlois, the film stars the voices of Jay Baruchel, America Ferrera, Cate Blanchett, Craig Ferguson, and F. Murray Abraham. The film's plot follows Hiccup seeking a dragon utopia called "The Hidden World" while coming to terms with Toothless' new bond with a female Light Fury.
How to Train Your Dragon: The Hidden World was released on January 3, 2019, in Australia, and on February 22 in the United States. The film was critically acclaimed and a box office success, grossing $525 million worldwide against its $129 million budget. It became the fifth highest-grossing animated film of 2019, as well as Universal's highest-grossing animated film not to be produced by Illumination. At the 92nd Academy Awards, the film was nominated for Best Animated Feature, losing to Pixar's Toy Story 4.
One year after the events of the second film, Hiccup continues to rescue dragons with his fellow Dragon Riders and friends. Even though he has fulfilled his dream of creating a utopia where humans and dragons live together, Hiccup still tries to save dragons and bring them to Berk while dreaming of finding the mythical 'Hidden World', a safe haven for dragons his late father Stoick told him about. Unfortunately, his efforts have also resulted in the island becoming severely overpopulated with dragons. Meanwhile, a white female dragon, held captive by the Warlords, is given to infamous dragon hunter Grimmel the Grisly as bait for him to capture Toothless for the Warlords' use as an Alpha.
Toothless discovers the female Fury (dubbed a "Light Fury" by Astrid) in the woods around Berk, the two quickly becoming enchanted with each other; yet, the Light Fury senses Hiccup's presence (him having followed Toothless) and flees. Hiccup and Tuffnut later discover Grimmel's dragon traps in the woods. Grimmel visits Hiccup that night, but the latter has prepared an ambush to capture him; Grimmel manages to escape, burning Hiccup's house in the process. Hiccup rallies Berk's citizens and dragons to leave Berk on a quest to find the Hidden World.
Mid-journey, the Berkians discover an island they initially plan to rest on; soon, they decide to settle there, even if only temporarily. Seeing Toothless's inability to fly solo hindering his growing relationship with the Light Fury, Hiccup builds him an automatic tail. Upon receiving the tail, Toothless flies off, meeting the Light Fury on his own and flying with her to an unknown land. On a scouting patrol, Valka notices Grimmel's approaching army, quickly reporting back to warn Hiccup. Hiccup and the Dragon Riders head to capture Grimmel; yet, they fall into his trap, barely escaping. Ruffnut, however, is captured but irritates Grimmel until he lets her go. Unknown to Ruffnut, she accidentally reveals the Berkians' new location, and Grimmel secretly follows her.
Hiccup and Astrid search for Toothless, finding the Hidden World and seeing Toothless and the Light Fury leading the dragons there as Alphas and mates. However, the two are soon discovered, Toothless being forced to leave and take Hiccup and Astrid back to the Berkians. Hiccup realizes his people wouldn't be safe living with dragons in the Hidden World, and moreover, have no business intruding upon the dragons' home. Suddenly, Grimmel, having followed Ruffnut, appears and captures Toothless and the Light Fury.
With Astrid's encouragement, Hiccup sets out with the Dragon Riders to stop Grimmel and his army and save Toothless, the Light Fury, and all the captured dragons. Gliding in on wingsuits, the group catches Grimmel's army off-guard, igniting a massive battle. Hiccup frees Toothless while Grimmel drugs the Light Fury into obeying him. Hiccup and Toothless give chase; after a heated aerial duel, Grimmel tranquilizes Toothless midair. Hiccup, realizing he cannot save Toothless by himself, frees the Light Fury instead and commands her to save the Night Fury. Hiccup and Grimmel plummet to the sea, with Hiccup fully accepting that this may be his end. However, the Light Fury unexpectedly returns to save Hiccup while allowing Grimmel to fall to his death.
The battle won; back on the island, Hiccup fully realizes that the dragons will likely never be safe in the human world and that the Hidden World is where they truly belong. Hiccup and Toothless bid farewell to each other with great sadness as all of the Berkians set their dragons free. Toothless and the Light Fury then lead the dragons to the Hidden World. Sometime later, Hiccup and Astrid get married as the Berkians settle permanently onto their new island. Years later, Hiccup, Astrid and their two children, Zephyr and Nuffink, sail across the sea to visit Toothless, the Light Fury, their three offspring, and Stormfly at the edge of the Hidden World; Hiccup vows that until mankind can coexist peacefully with dragons, the dragons will stay hidden while the Berkians guard their secret.
- Jay Baruchel as Hiccup
- America Ferrera as Astrid Hofferson
- F. Murray Abraham as Grimmel the Grisly 
- Cate Blanchett as Valka
- Gerard Butler as Stoick
- Craig Ferguson as Gobber
- Jonah Hill as Snotlout
- Christopher Mintz-Plasse as Fishlegs
- Kristen Wiig as Ruffnut
- Kit Harington as Eret
- Justin Rupple as Tuffnut
- Robin Atkin Downes as Ack
- Kieron Elliott as Hoark the Haggard
- Julia Emelin as Griselda the Grievous
- Gideon Emery as Trapper
- Ashley Jensen as Phlegma the Fierce
- AJ Kane as Young Hiccup
- Ólafur Darri Ólafsson as Ragnar the Rock
- James Sie as Chaghatai Khan
- David Tennant as Spitelout Jorgenson and Ivar the Witless
- Unknown as Zephyr
- Unknown as Nuffink
- Crimson Goregutter
- Deadly Nadder
- Hideous Zippleback
- Light Fury
- Monstrous Nightmare
- Night Fury
In December 2010, DreamWorks Animation CEO Jeffrey Katzenberg announced that there would also be a third film in the series: "How To Train Your Dragon is at least three: maybe more, but we know there are at least three chapters to that story." In June 2011, Dean DeBlois, the writer and director of the second and the third film, stated that How to Train Your Dragon 2 was being intentionally designed as the second act of the trilogy: "There are certain characters and situations that come into play in the second film that will become much more crucial to the story by the third." In April 2012, DeBlois said in an interview that the third part would be released in 2016. In August 2012, author Cressida Cowell revealed that the trilogy and the book series will have similar endings (with "an explanation as to why dragons are no more").
In September 2012, 20th Century Fox, the studio's then-distributor partner, and DreamWorks Animation announced the film was originally going to be released on June 17, 2016. It was also revealed that the film was going to be produced by Bonnie Arnold and Brad Lewis. DeBlois and Chris Sanders were the executive producers; Sanders was an executive producer of the second film and co-director of the first. And Jay Baruchel, Gerard Butler, Craig Ferguson, America Ferrera, Jonah Hill, Christopher Mintz-Plasse and Kristen Wiig were revealed to return in the third film. 
In September 2014, the film's release date was delayed to June 9, 2017, and Cate Blanchett was revealed to reprised her role as Valka from the second film. In October 2014, DeBlois explained the release date shifts as such: "It's just that these movies take three years. I think it was a little ambitious to say 2016... As is normally the case, they kind of throw darts out into the future and wherever they land they call that a release date until we start talking about it in practical terms, and then it's like, 'Uh yeah that's not enough time'. So knowing that they take three years from this moment, from outlining and writing the screenplay through to the final lighting of it, it's just a process of building models and doing tests and animating, storyboarding, the whole thing just adds up to about three years." In January 2015, the release date was delayed to June 29, 2018 following DreamWorks Animation's corporate restructuring and lay-offs meant to maximize the company's "creative talent and resources, reduce costs, and drive profitability." In February 2015, DeBlois stated that Djimon Hounsou would also return as Drago Bludvist. In November 2017, it was announced that Kit Harington will reprise his role as Eret and F. Murray Abraham has joined the cast. In April 2018, DreamWorks Animation announced that the sequel's title would be How to Train Your Dragon: The Hidden World.
In January 2019, Justin Rupple was revealed to be replacing T.J. Miller as Tuffnut. In February 2019, DeBlois revealed that Miller did initially return to voice Tuffnut, but DreamWorks recast him after the actor's sexual misconduct, assault allegations and arrest for calling in a fake bomb threat.
- It is Universal Pictures' second animated theatrical film released in February, after Curious George in 2006.
- This also marks DreamWorks Animation's first trilogy to have each installment distributed by a different studio over the years (Paramount distributed the first movie in 2010, and Fox distributed the second movie in 2014) Along with second trilogy that have each installment distributed by a different studio over the years.
- How to Train Your Dragon 3 would be DreamWorks Animation's film with numerous changes of release date. First, it was scheduled for release on June 18, 2016, which was later changed to June 17, 2016. Then, the release date was moved to June 9, 2017 until it was pushed back to June 29, 2018, which was later moved up to May 18, 2018, taking over the release date of Warner Animation Group's The Lego Movie 2: The Second Part. After that, the release date was pushed back again to March 1, 2019. Finally, on September 27, 2018, it was pushed back to February 22, 2019.
- The film was first titled How to Train Your Dragon 3, but on April 17, 2018, the title has changed to How to Train Your Dragon: The Hidden World.
- The second DreamWorks Animation film to be rated PG for adventure action and some mild rude humor by the MPAA, after How to Train Your Dragon 2.
- This is the first time T.J. Miller does not voice Tuffnut in the How to Train Your Dragon trilogy.
- This is the first DreamWorks animation film to use the 2019 DreamWorks logo.
- This is the first DreamWorks Animation film that streamed on Huluinstead of Netflix.
- Its wait of 1 year and 8 months after the release of Captain Underpants: The First Epic Movie, which was released on June 2017, is the longest wait between two DreamWorks films and its predecessor in the studio's history, surpassing the 1 year and 3 month wait between The Prince of Egypt, which was released on December 1998, and The Road to El Dorado, which was released on March 2000.
- This film was the first DreamWorks Animation film that used the new animation and rendering system named "Premo" and "MoonRay".
- Deadline.com  Anthony D'Alessandro, November 14, 2017