Grawp is the giant half-brother of Hagrid in the Harry Potter books. In the film adaptation of the book Grawp is completely computer-generated using a new "soul capturing" process from Image Metrics..Andrew Whitehead spent 18 months working on the giant Grawp for the film. The voice of Grawp is performed by Tony Maudsley.
First introduced in Harry Potter and the Order of the Phoenix, Grawp is brought from his mountain home to the Forbidden Forest outside Hogwarts by Hagrid. Grawp and Hagrid were born of the same mother, the giantess Fridwulfa; Hagrid's father was a wizard, whereas Grawp's father was a giant. Grawp is about 16 feet (4.9 metres) tall, which Hagrid claims is small for a giant. His knuckles are the size of a cricket ball (~225 mm in circumference). The other giants were bullying Grawp, and this was a factor in Hagrid's decision to bring him to the Forbidden Forest. Big and dim, he only knows a few words in English and his manners are wild and unpredictable. At first, he seemed indifferent to his brother's attempts to civilise him, preferring to spend his time tearing down trees.
When Grawp first appears in the Order of the Phoenix, Hagrid takes care of him, but must keep him tied to multiple trees simultaneously. However, after Hagrid leaves Hogwarts to continue his work for the Order of the Phoenix, he leaves Grawp in the care of Harry, Ron, and Hermione. Much to their surprise, when they find themselves trapped in the forest during a confrontation with the local centaur population, Grawp inadvertently manages to divert the centaurs' attention from Harry and Hermione. At the time, Grawp displays considerable distress at being unable to find his brother Hagrid, whom he calls 'Hagger'. He also remembers Hermione, calling her "Hermy" (a shorter form suggested by Hagrid because he felt Grawp would not be able to pronounce the full name).
In Harry Potter and the Half-Blood Prince, Grawp is moved to the mountains, where he is apparently progressing much better. He also attends Dumbledore's funeral with Hagrid, much more civil and calm than before, and dressed formally. He also appears to understand emotions, at least to some extent, as he pats Hagrid's head to comfort him. In Harry Potter and the Deathly Hallows, Grawp, Hagrid, and Fang go into hiding after Hagrid throws a "Support Harry Potter" party and it is implied that Grawp helped them all escape. He is the only Giant fighting against the Death Eaters in the Battle of Hogwarts, and carries Hagrid from their hiding place to the castle on Hagrid's request (shoving him through a window in the process). This is probably borne out of a desire to protect Hagrid, as he frequently calls his name while fighting the Death Eaters. Grawp participates in the victory celebration over Voldemort's defeat (albeit from a window, since he is too big to fit into the hall), and the Hogwarts students show their appreciation by tossing food into his laughing mouth.