- “The saga of friendship comes an epic conclusion.”
How To Train Your Dragon: The Hidden World is a 2019 computer animated film, due to be released on February 22, 2019 in USA. The second sequel in the series and the third and final installment of How to Train Your Dragon trilogy was directed and written By Dean DeBlois and produced by Bonnie Arnold. The film was executive produced by Dean DeBlois and Chris Sanders. It was produced by DreamWorks Animation and distributed by Universal Pictures, making it the first DWA film to be distributed by Universal after its parent company NBCUniversal bought DWA in 2016.
The film received widespread critical acclaim and has grossed $438 million worldwide against it's $129 million budget.
One year after the events of the second film, Hiccup continues to rescue dragons with his fellow Dragon Ridersand 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 which they initially plan to rest on; soon, though, they decide to settle there, even if only temporarily. Seeing Toothless' 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. Valka, on a scouting patrol, 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 has accidentally revealed 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 catch 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. The Light Fury, however, 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. With great sadness, Hiccup and Toothless bid farewell to each other 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
- It is Universal Pictures' second animated theatrical film released in February, after Curious George in 2006.
- 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 in 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 only time T.J. Miller does not voice Tuffnut in the How to Train Your Dragon trilogy.