The raven and/or crow is connected to Apollon. For a variety of reasons, Hermes is often associated with these birds as well, but there is no ancient evidence for this. Apollon, on the other hand, has a long history with the birds. It seems odd that a deity associated with light is also associated with an animal with an image as negative as the raven. Ravens are often associated with battlegrounds, cemeteries, and death, with the rotting of carcasses, and funerals. In Hellenic myth, they are also associated with vision beyond that which is present. With oracular visions, and with spotting that which can not, or should not, be spotted.
One myth associated with the constellation Corvus is that of Apollo and Koronis (Κορωνίς). Koronis was Apollon's lover, and was pregnant with His son, when she fell for another man, a mortal man, Ischys (Ἰσχύς). A raven--then white--had been assigned by Apollon to watch over His lover, and when the raven returned to tell Apollon of Coronis' betrayal, Apollon was furious the raven had not pecked out the eyes of the mortal whom his lover fell in love with. In a fit of rage, Apollon turned its feathers black. Apollodorus wrote about this event (3:10:3), and the events that followed:
"Besides them Leucippus begat Arsinoe: with her Apollo had intercourse, and she bore Aesculapius. But some affirm that Aesculapius was not a son of Arsinoe, daughter of Leucippus, but that he was a son of Coronis, daughter of Phlegyas in Thessaly. And they say that Apollo loved her and at once consorted with her, but that she, against her father's judgment, preferred and cohabited with Ischys, brother of Caeneus. Apollo cursed the raven that brought the tidings and made him black instead of white, as he had been before; but he killed Coronis. As she was burning, he snatched the babe from the pyre and brought it to Chiron, the centaur, by whom he was brought up and taught the arts of healing and hunting."
In another myth, Corvus represents a raven or crow in service to Apollon, who was sent out on an errant for the Theos. He was asked to bring water to Him, but instead, he paused in his quest, most commonly assumed is that he stopped for a meal of figs. When the raven returned without water, Apollon questioned him. Instead of giving a straight answer, the raven lied, and said he had been kept from the water by a snake. In some accounts, he actually had a snake in his talons as he said this. Apollon, however, saw that the raven was lying, and flung the raven, the krater with which the raven was supposed to collect water, as well as the snake into the sky, where they remain to this day. To punish the bird further, Apollon made sure the krater would forever be just out of reach of the bird.
This Apollon-oriented constellation is visible at latitudes between +60° and −90°, and best visible at 21:00 (9 p.m.) during the month of May.