Charon, the ferryman of the Greco-Roman underworld, was born from a union of the primordial embodiments of night (Nyx) and darkness (Erebus). Charon’s many siblings included Aether (upper air) Hemera (daytime), Thanatos (death), Hypnos (sleep), the Oneiroi (dreams), Geras (old age), Nemesis (retribution), the Moirai (the fates), and the Hesperides (the Nymphs who guarded Hera’s golden apples). As with most Greco-Roman mythology the offspring of Nyx and Erebus differ between mythological accounts, but it was a prolific union, nonetheless.
Charon was a god, albeit a minor one, but it was his cosmological employment which made him a household name. Charon was the ferryman of the underworld, tasked with navigating the many rivers of the underworld, and carrying those souls which were newly departed to their new resting place. Initially he rowed these souls across the Acheron River, but this was replaced by the river Styx in some later accounts.
Charon’s appearance suited his task; a surly old Captain who had full control on his vessel. In the Aeneid Virgil describes him quite memorably:
A ferryman of gruesome guise keeps ward
Upon these waters,—Charon, foully garbed,
With unkempt, thick gray beard upon his chin,
And staring eyes of flame; a mantle coarse,
All stained and knotted, from his shoulder falls,
As with a pole he guides his craft, tends sail,
And in the black boat ferries o’er his dead; – Virgil, The Aeneid XI
There are a number of references to Charon’s fiery flashing eyes and advancing age. Charon is an old god, but still has life and power within. He, like most gods, expects to be recognized for his role, but unlike the others that accept various forms of payments in adoration and sacrifices, Charon has a flat fee for his service, and it is non-negotiable. Greek burial customs insisted that a coin be placed inside the mouth of the deceased, the fare to pay Charon for his services. Those without payment were left to wander the banks of the river… ghosts in eternal limbo.
Directly after that you will come to the river of death. Its harbourmaster is Charon, who ferries wayfarers to the other bank in his boat of skins only on payment of the fee which he immediately demands. So it seems that avarice lives even among the dead, and a great god like Charon, Dis’s Collector, does nothing for nothing. – APULEIUS, The Golden Ass
Charon also insists that his passengers are deceased, refusing passage to those who are still living except in the rarest of circumstances. Orpheus managed to charm the ferryman with his music on his quest to retrieve Euridice, whereas Heracles took a more direct approach and just beat Charon over the head until he agreed. Thankfully for those of us who have read the Aeneid and ever need to take a brief jaunt through the underworld – and intend to come back – there is a loophole, the golden bough! Hidden in the woods, this branch grows hidden amongst the branches of tall trees. Locating it is just part of the quest though; for it will only break off for those that are worthy of it. Sacred to Persephone, the golden bough is an all-access pass through the underworld.
Far in the grove it hides; in sunless vale
Deep shadows keep it in captivity.
No pilgrim to that underworld can pass
But he who plucks this burgeoned, leafy gold – Virgil, The Aeneid XI
Charon has remained in the popular consciousness, appearing in film, television, games and comic books. He also has one of the moons of Pluto named in his honor, as well as a dinosaur, the Charonosaurus (the Charonosaurus was named after it was found in 2000 by Godefroit, Zan & Jin in the dark mud along the Amur (Black Dragon) river that separates the borders of China and Russia). He also lives on in the incarnation of another; Charos, the god of death in modern Greek folklore (Sullivan). This version of Charon is more like the grim reaper, and his boat is gone, but his essence still lives on as the angel of death, tirelessly transporting souls to the world below.

References
APULEIUS, The Golden Ass, E. J. KENNEY trans. Penguin Books 1998
Sullivan, Francis A. “Charon, the Ferryman of the Dead.” The Classical Journal, vol. 46, no. 1, 1950, pp. 11–17. JSTOR, http://www.jstor.org/stable/3293423. Accessed 14 Jan. 2021.
Virgil. Aeneid. Theodore C. Williams. trans. Boston. Houghton Mifflin Co. 1910