The name Harry is used as a nickname both of Henry
(French origin) = "home ruler", and Harold (Scandinavian origin) = "army ruler".
In The Order of the Phoenix Harry becomes the leader of a group of Hogwarts students who call themselves "Dumbledore's Army".
Ron, Ronald: (Old Norse) = "Ruler's counselor."
Hermione: (Greek) = "Messenger; earthly." Femine form of Hermes. Hermes was a messenger for the gods on Olympus and was himself the god of eloquence. Hermione is a witch, but Muggle-born. She reads a lot, knows a lot, talks a lot - and provides a lot of useful information.