There are numerous number of dragons, created by a lot of writers from ancient times.  Even now, we see various kinds of them through books or movies, like "Hobbit" and "Harry Potter." 
As for me, I got to know some of them through those kind of fantasy movies or books.  In my image, dragons have big and rough bodies with pairs of large wings, parts of which are teared and damaged.  To describe them simply, they are like smart dinosaurs with much lighter bodies and freedom in the air.  Most of them can brearh fire freely, and they seem to be stronger than any other animals on the earth.  Usually, they have some roles, like guarding something important.  In the movie, "Shrek" one red dragon is guarding a princess in a castle.  And though many of them are reagarded as a brutal bad animals, some of them sometimes can be good companies, like in "The Chronicles of Narnia 3" and "Shrek."  Anyway, dragons are one of the most exciting characters, and plays important roles in many movies!