This story from Norse Mythology (Icelandic) stems from the late 13th century. Fafnir, one of two brothers, plots to take the fortune of his father, Hreithmar. Once he steals his father’s house of glittering gold, he uses his power to turn into a Lindworm (a dragon without wings or hindlegs) to guard the treasure and keep his brother Regin away from it. Eventually Fafnir and his scheming brother Regin are both foiled by Sigurd, a courageous man of noble heritage and his magical sword, Gram.
In Western mythology, dragons often protect valuable items and treasures, which is why they’re associated with greed. Recent examples of this are Smaug, the dragon found in The Hobbit, and the wyvern guarding the underground vaults of Gringots Bank in Harry Potter and the Deathly Hallows.