Ralph Deedle is a thoughtful, and awkward large boy who befriends James Potter (Harry Potter's eldest son) and Zane Walker on the Hogwarts Express before their first year at Hogwarts. His father, Dennis, is an unemployed computer security software designer and was surprised when Ralph got his letter from Hogwarts. Despite the fact that Ralph had been sorted into Slytherin, he maintains his friendship with James, much to some older Slytherins' chagrin. Ralph owns a GameDeck (to those Slytherins' even greater chagrin), on which he has given himself the screen name "Ralphinator," a portmanteau of "Ralph" and "Terminator." For years to come, this would be the nickname that Zane would often refer to him by.
He was elected prefect in his fifth year, and in his seventh year, becomes the Slytherin Head Boy.
Ralph, commonly short for a name such as "Rudolph," comes from the Hebrew name (Rafa'el) meaning "to heal." Which could refer to how Ralph has to succumb to his infamous family legacy and accept it ('healing' his family reputation, in the process). But it's also likely that this could symbolize his father telling Ralph the truth that he's been hiding, helping to mend and strengthen their relationship.
Ralph is also the name of one of the characters in the book, Lord of the Flies, where he symbolized civilization and democracy.