Luna Lovegood

She's a good and true friend.
She always supports the team.
She can be a little weird,
But you know what I mean.
She's smart and cunning,
And quick to act.
She believes in a thing called a
Crumble-Horned Snorckack.
You still don't know who she is?
Now, you really should!
She's a Ravenclaw 4th year
Named Luna Lovegood!

(I didn't write this!) Source here.