This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Ladon (Greek)
Ladon was the serpent-like dragon that twined and twisted around the tree in the Garden of the Hesperides and guarded the golden apples. In pursuance of his eleventh labour, Heracles killed Ladon with a bow and arrow and carried the apples away.
Ladon was a serpent of notable size—the equivalent, perhaps, of what we would now call a “dragon.” In one tradition, he had one hundred heads and many terrifying voices, much like the monster Typhoeus. But this seems to have been an idiosyncratic description, with most sources representing Ladon with only one head.