Rubeus Hagrid was one of the first characters Rowling created.[1] In a 1999 interview, she explained that the name "Hagrid" is an Old English word. She said it means "you'd had a bad night" and she explained that Hagrid "has a lot of bad nights" due to his heavy drinking.[2] In Latin, "Rubeus" means "red", and was chosen because Rowling conceived of Hagrid as an "earthy, warm, and physical man".[3]

The character of Hagrid and conversations between him, Harry Potter, Ron Weasley and Hermione Granger in his hut are expository through the series, due to the fact that the trio frequently discover things about Albus Dumbledore and Hogwarts by talking with Hagrid, as he has a habit of letting slip bits of information that were specifically confided to him. He was also one of the first characters to imply that the idea of thinking of wizards as "pure-bloods" and "half-bloods" is a dated concept.

Rowling has stated in an interview that Hagrid was in Gryffindor house during his time as a student.[4] When he comes into possession of an acromantula, he is expelled from Hogwarts as his pet is believed to be the "monster of Slytherin". However, persuaded by Dumbledore (who at the time was Transfiguration teacher), Headmaster Armando Dippet agrees to train Hagrid as gamekeeper, allowing the boy to remain at Hogwarts. By the time Harry attends Hogwarts, Hagrid is also the Keeper of Keys and Grounds; the former, according to Rowling, means "that he will let you in and out of Hogwarts."[5] Part of his job includes leading the first years across the lake in boats, upon their initial arrival at Hogwarts.