I would think that most people have read a Harry Potter novel or seen a Harry Potter movie, in fact, I think that it would be considered odd if you haven't. Their can be many reasons for his popularity, some being how he looks and acts like an average "guy" even though he is a wizard with great power, as well as his quest for identity when his parents are killed after childbirth. J.K Rowling does a great job of displaying the struggle that Harry has had growing up, from living with his aunt and uncle who treat him like garbage to trying to contain the magic that lies within and not exposing himself to the "muggle world". The reader is able to easily relate to the realistic story in a completely different universe where magic exists and normal beings aren't aware of the it.
Another key skill that J.K Rowling possess' is her ability to maintain interest throughout a 800 page novel, as there are many other books that fall apart due to a really boring lead up to the climax. This is why millions of people have read all eight of her books, as they are enjoyable to read throughout. As refered to before, all the Harry Potter books contain very realistic stories. A part of that realism is that as the reader grows older, so does Harry. Especially for readers such as myslef who are around the same age as him, Harry Potter progressively matures and experiences new things. This allows the reader to become captivated because of the chances of them experiencing the same things that Harry does, such as defending against bullies or uncompassionate family members.
J.K Rowling uses not just archetypes surrounding characters but also around places or events. As Harry is sent to Hogwarts, it acts as a modern boarding school, a common occurence in many older books. She uses this to establish a connection with the reader to other books he/she might have read and allows for easier understanding of the situation Harry Potter is in. Another common archetypes used is the family Harry lives with, as they lock him up in his room and treat him like a slave, not a human. Many main characters of other books have families that despise them, and so they wish to escape. As the antagonist, Lord Voldemort draws many comparisons to devil, a being very commonly recongnized as being pure evil. As an archetype, Voldemort stands as both the Devil Figure as well as the Creature of Nightmare, attempting to block Harry in his path to destroy all evil. Are their any other famous book series that have reasons behind their popularity related to archetypes?