“Well — half-brother,” amended Hagrid. “Turns out me mother took up with another giant when she left me dad, an’ she went an’ had Grawp here —”
“Grawp?” said Harry.
“Yeah . . . well, tha’s what it sounds like when he says his name,” said Hagrid anxiously. “He don’ speak a lot of English. . . . I’ve bin tryin’ ter teach him. . . . Anyway, she don’ seem ter have liked him much more’n she liked me. . . . See, with giantesses, what counts is producin’ good big kids, and he’s always been a bit on the runty side fer a giant — on’y sixteen foot —”
-Harry Potter and the Order of the Phoenix, Chapter Thirty (Grawp).
Is it ever revealed anywhere what Grawp's real name is?