Based on the 2003 book How to Train Your Dragon is a 2010 3D computer-animated fantasy film by DreamWorks Animation.The story takes place in a mythical Viking world where a young Viking teenager named Hiccup aspires to follow his tribe's tradition of becoming a dragon slayer. After finally capturing his first dragon, and with his chance at finally gaining the tribe's acceptance, he finds that he no longer has the desire to kill it and instead befriends it.The island of Berk has been plagued by attacks from dragons that steal their livestock and burn their homes. Hiccup, the awkward son of the village chieftain, Stoick the Vast, uses a cannon contraption he invented and shoots down a dragon he thinks may be a Night Fury, a rare dragon nobody has ever actually seen. Hiccup locates the dragon in the forest, but finds he is unable to kill the helpless animal. Hiccup instead cuts it free, and the dragon disappears into the forest. Meanwhile, Stoick assembles a fleet to seek out the dragons' nest, but before he leaves, he places Hiccup in dragon-killing classes taught by Gobber, the village blacksmith.Searching the forest, Hiccup finds the dragon trapped in a shallow glade; the dragon's tail was injured, preventing it from flying normally. By trial and error, Hiccup discovers a way to earn the dragon's trust and begins to care for it. He names the Night Fury "Toothless," for its retractable teeth. Hiccup wins the class and gets the chance to kill a dragon in front of the entire village.Astrid follows Hiccup, suspicious of his sudden skill, and is shocked to discover Toothless. She attempts to escape to tell the rest of the village, but Hiccup coerces Astrid into flying with Toothless. At first, Astrid is terrified, but then begins to enjoy the excursion. Toothless unexpectedly joins a flock of dragons and takes the pair straight into the dragon's nest, where the truth behind the dragons' constant raids of their village is revealed - a gigantic dragon lives off the food they bring back, else it feeds on the dragons themselves.
Hiccup is put to his final exam the next day, but when he tries to show the village the dragon's true nature, Stoick stops the fight, inadvertently angering the dragon and endangering Hiccup. Toothless hears Hiccup's cries and flies in to save him, but is captured himself. Hiccup, attempting to explain his actions, reveals how to find the dragons' nest. He tries to warn his father of the danger, but Stoick refuses to listen to his son, disowns him, and sets off with another fleet, using a restrained Toothless as their guide. Astrid inspires Hiccup to concoct a plan to save the Vikings with the help of the school's captive dragons and his classmates.
The teens arrive after the Viking fleet has already uncovered the gargantuan dragon. Hiccup's classmates distract it while Hiccup goes to save Toothless. Hiccup and Toothless almost drown, but both are saved by a now-repentant Stoick. Hiccup and Toothless lure the giant dragon into flight, ultimately setting fire to the flammable gas inside its mouth and forcing it into an inescapable dive back to earth. Attempting to flee from the crashing dragon, Hiccup falls off Toothless, and Toothless dives into the flames after him.His grief is turned to joy however, as he steps outside to find the Vikings and dragons working together to rebuild their village.