Riddle Me This

Down below are a few riddles. See if you can figure all of them out. I'd be impressed if you could!

~I am something feared by some
but others know better.
For four years he had looked without seeing me
but I was seen in the fifth.
Ron may think you're crazy to see me,
but don't worry; you're just as sane as Luna.

~The first wasn't who you thought you'd see at the end;
the sixth one was.
The second turned out to be less than was expected
but the third turned out to be more-
or at least for most.
The fourth and seventh were cut from the same cloth
and the fifth decided to make their role much more.

~I'm one of the seven
made by this famous person,
whose name is never said
by the people in that world.
Inside of me one little girl
opened up too much of her heart.
And one famous boy
discovered his enemy's true name.
When I eventually met my end
a part of evil's terrible
reason that he survived,
met it's end as well.
But wait before you answer
and keep this information in mind:
Piercing my pages with a Basillisk fang
wouldn't case me to bleed
.
~What I want, I take,
what I need, I make.
I'm certainly charming,
but that much is fake.
I kill muddy vermin,
leaving death in my wake.
You best not anger me,
for your own sake.
For I'm the world's most powerful snake.

I'll only post four for now. I may post more if people want to solve them. These riddles do not belong to me, apart from the last one.