In Greek myths, Ladon, the great dragon, guarded the golden apples of the Hesperides. As one of Hercules' 12 labors, he killed Ladon. In Greco-Roman myth, Draco was killed by the goddess, Minerva. The constellation of Hercules is close to Draco.
Draco was discovered by the Greek astronomer, Ptolemy, in the 3rd century. Ptolemy discovered a good portion of the other constellations.