Ladon (Λάδωνας in Ancient Greek) is the dragon who guards The Garden of Hesperides.
Unfortunate people who try to steal the golden apples
Has basic dragon Biology but has no flight bladders and a very powerful nero-toxic venom
A huge green dragon with multiple heads
Ladon was the serpent-like dragon that twined and twisted around the tree in the Garden of the Hesperides and guarded the golden apples. He was overcome by Hercules. The following day, Argonauts passed by, on their chthonic return journey from Colchis at the opposite end of the world, and heard the lament of "shining" Aigle, one of the Hesperides, and viewed the still-twitching Ladon.
Ladon was given several parentages, each of which placed him at an archaic level in Greek myth: the offspring of "Ceto, joined in heated passion with Phorcys" or of Typhon, who was himself serpent-like from the waist down, and Echidna or of Gaia herself, or in her Olympian manifestation, Hera: "The Dragon which guarded the golden apples was the brother of the Nemean lion" asserted Ptolemy Hephaestion. In one version, Hercules did not kill Ladon. The creature is associated with the constellation Draco.