How to Train Your Dragon: The Hidden World (also known as How to Train Your Dragon 3) is a 2019 American animated fantasy film loosely based on the book series by Cressida Cowell. Produced by DreamWorks Animation and distributed by Universal Pictures, it is the sequel to How to Train Your Dragon 2 (2014) and the final film in the How to Train Your Dragon trilogy. Written and directed by Dean DeBlois and produced by Bonnie Arnold and Brad Lewis, the film stars the voices of Jay Baruchel, America Ferrera, Cate Blanchett, Craig Ferguson, and F. Murray Abraham, with Gerard Butler, Jonah Hill, Christopher Mintz-Plasse, Kristen Wiig, Justin Rupple (replacing T.J. Miller), and Kit Harington in supporting roles. The film follows 21-year old Hiccup seeking a dragon utopia known as the "Hidden World" while coming to terms with Toothless's new bond with a female Fury, as they deal with the threat of Grimmel the Grisly, a ruthless dragon hunter.

Discussions regarding a third How to Train Your Dragon film began in December 2010, with DeBlois later stating that the second film was being intentionally designed as the second act of the trilogy. The film underwent various changes in its release date due to distributor changes. The animation challenges of the production required DreamWorks Animation to update and invent new software to handle complex tasks, such as lighting the Light Fury dragon.

How to Train Your Dragon: The Hidden World was released on January 3, 2019, in Australia, and on February 22 in the United States. Like its predecessors, it received positive reviews from critics, with praise for its animation, voice acting, musical score, and emotional weight. The film grossed over $525 million worldwide. It received several accolades: five Annie Awards nominations, a Golden Globe nomination, and a nomination for Best Animated Feature at the 92nd Academy Awards. A live-action reboot of the franchise is scheduled to be released in June 2025.