Very sparse mild language. A few uses of 'Oh my God' or similar exclamations (Viking context). The word 'hell' may appear once or twice in a Viking cultural context (referring to Norse concepts). No profanity beyond this level.
Significant but non-graphic fantasy violence throughout. Vikings battle dragons with axes, swords, hammers, and catapults. Dragons breathe fire, destroying buildings and carrying off livestock. Hiccup shoots down Toothless with a bola launcher. A massive dragon (the Red Death/Green Death) threatens lives in the climactic battle. Hiccup loses his left foot/lower leg in the final battle (revealed when he wakes with a prosthetic — handled tastefully, not graphically). Vikings are thrown, knocked around, and singed. A dragon training arena features teens facing dangerous dragons. Some scenes could frighten younger children, particularly the enormous final dragon and the intensity of fire-breathing attacks.
Exceptionally strong positive values. The film powerfully teaches: (1) Compassion and mercy over violence — Hiccup refuses to kill a helpless creature and chooses kindness, even at great personal cost. (2) Courage to stand alone — Hiccup defies his entire culture to do what is right. (3) Father-son reconciliation — Stoick and Hiccup's broken relationship is beautifully restored when Stoick sees the truth and repents of his stubbornness. (4) Sacrificial love — Hiccup risks his life to save his village, and Toothless risks his life to save Hiccup. (5) Peacemaking — the resolution involves making peace rather than perpetuating a cycle of violence. (6) The value of every person — Hiccup is small, weak, and different but proves that worth is not determined by physical strength. (7) Consequences of prejudice and assumptions — the Vikings were wrong about dragons, and humility to change is portrayed as strength.
As the son of a Viking leader on the cusp of manhood, shy Hiccup Horrendous Haddock III faces a rite of passage: he must kill a dragon to prove his warrior mettle. But after downing a feared dragon, he realizes that he no longer wants to destroy it, and instead befriends the beast – which he names Toothless – much to the chagrin of his warrior father.