Charon

During the Dark Age, the Gods warred on more than the material plane. There were conflicts on the other planes, and travel between realms was eventually targeted to close off each side. Methods of doing so were explored, and as these were employed, the ways to travel between the realms and planes were slowly destroyed, making it extremely difficult to traverse them.
During this time, a mysterious entity appeared and started offering services to transport others to the realms and planes; of course, it did not do this for free, and a price would be paid by those who wished to travel. Said price changed depending on where the person wanted to go and how many. One thing that became apparent, though, was this being had no allegiances to anyone as it offered its services to everyone in exchange for payment; however, there were times it denied its services to those who sought to steal from it or those who tried to force it to ferry them. Such people found that the Ferryman was more than a match for most beings and perhaps even the gods.
When the Divine Barrier was raised, the rumors of the Ferryman persisted. Many believe this being is still looking for people to ferry, as long as you have coin for the ride.