The Brothers Lionheart (Swedish: Bröderna Lejonhjärta) is a children's fantasy novel written by Astrid Lindgren. It was published in the autumn of 1973 and has been translated into 46 languages. Many of its themes are unusually dark and heavy for the children's book genre. Disease, death, tyranny, betrayal and rebellion are some of the dark themes that permeate the story. The lighter themes of the book involve platonic love, loyalty, hope, courage and pacifism.

The two main characters are two brothers; the older Jonatan and the younger Karl. The two brothers' surname was originally Lion, but they are generally known as Lionheart. Karl's nickname is Skorpan (Rusky) since Jonatan likes these typical Swedish toasts or crusts.

In Nangijala, a land in "the campfires and storytelling days", the brothers experience adventures. Together with a resistance group they lead the struggle against the evil Tengil, who rules with the aid of the fearsome fire-breathing dragon, Katla.