According to a version of the myth of Ganymede, Zeus fell in love with this very handsome youth, and took the form of an eagle to be able to seize him and carry him up to the Olympus mount, just as on other occasions he had taken the form of different animals to satisfy his lust. The bird was therefore immortalized in a constellation.
According to other myth-writers, Prometheus stole fire from Zeus and gave it to mortals. The god then inflicted eternal punishment on him for this crime, by having him bound to a rock while an eagle ate his liver out in daytime, to have it grow back at night-time to be eaten again the next day. Eventually Prometheus was saved by Heracles, who shot an arrow against the eagle.
The constellation is located in the Milky Way and is therefore rich with star fields and novae.