Short answers, pulled from the story.
Oberon was discovered by William Herschel on the 11th of January 1787. On that same night, he also discovered Titania, making it a double discovery. For nearly fifty years after, no other telescope could detect either moon.
All moons of Uranus are named after characters from the works of William Shakespeare or Alexander Pope. Oberon takes its name from the King of the Fairies in Shakespeare's A Midsummer Night's Dream. The name was formally suggested by John Herschel in 1852 at the request of astronomer William Lassell.
Oberon may have a liquid ocean up to 40 km thick at the boundary between its rocky core and icy mantle, held at around 180 K. This would require enough ammonia or other antifreeze compounds to be present in the ice. Recent analysis favors active subsurface oceans in the larger Uranian moons, but Oberon's thermal history remains poorly known.
Voyager 2 is the only spacecraft to have visited Oberon, making its closest approach in January 1986 at a distance of 470,600 km. The flyby mapped roughly 40% of the surface, with only about 25% at a resolution suitable for geological mapping. No other spacecraft has visited the Uranian system.
The largest known crater on Oberon is Hamlet, measuring 206 km in diameter. Like the craters Othello and Macbeth, Hamlet's floor is covered by a very dark material deposited after the crater itself formed. All named surface features on Oberon are drawn from male characters and places in Shakespeare's works.
Oberon orbits Uranus in approximately 13.5 days. Its rotation period matches its orbital period, meaning the moon is tidally locked with one face always pointing toward Uranus. It orbits at a distance of about 584,000 km, making it the farthest of the five major Uranian moons.