The original story was Sigurd and Fáfnir if you would like to learn about this very old story which has remained alive even today (as you can see from this post) The story is much older than even the Völsunga saga, its written form, and it existed as oral tradition and art such as the Ramsund Carving. The dragon from Beowulf was an English version which drew on the existing Germanic/Norse legends and is also an excellent piece of our cultural history. Amazing to think that thousands of years ago our ancestors were entertaining themselves with the same meme we're chuckling about today.