In the 13th-century Huon of Bordeaux, Auberon is the son of Julius Caesar (!) and Morgan le Fay (!!). In the following century, there was a prequel, Roman d' Auberon (Romance of Auberon) more backstory is given. Here we learn that Auberon's great-grandfather was Judas Maccabeus, and his twin brother is St. George the Dragon Slayer.
Some of these ideas stick around. Ogier le Danois has Oberon as Morgan’s brother. In the play "Fairy Pastoral, or Forest of Elves," by William Percy (1603), Oberon's father and the previous king of the Fairies was named Julius, although the author apparently also considered the name Olbion.
In The Faerie Queen, Oberon is the son of Elficleos. (In this cosmology, Elficleos stands for Henry VII, Elferon is Prince Arthur, and Oberon is Henry VIII. And there are way more Elf names. It's a little annoying.)
In "Oberon, the Faery Prince," a masque by Ben Jonson (1616), Oberon (representing/played by Prince Henry Frederick) is the heir to King Arthur (James I).
This is an interesting reversal of stories such as the thirteenth-century Huon of Bordeaux, where Arthur is a prospective heir of Oberon, though the fairy king ultimately chooses Huon as his successor.
This seems like a good point to tie in to other heirs of Oberon.
Children of Oberon
In Spenser's The Faerie Queen (1590), Oberon's daughter Tanaquill rules after him and takes the royal name Gloriana. King Arthur is wooing her.
In the children's play "The Court of Oberon, Or The Three Wishes: A Drama in Three Acts," (1831) by Elizabeth Yorke, Gloriana is the princess and daughter of Oberon and Mab.
In The mad pranks and merry jests of Robin Goodfellow (1628), Robin Goodfellow is the son of Oberon and a mortal woman.
In the poem Kensington Gardens, by Thomas Tickell (1722), Oberon's daughter is named Kenna. She tragically falls in love with a human changeling and lends her name to Kensington Gardens. There was also a comic opera that was a sort of fan sequel to this, A Princess of Kensington (1903).
In the masque The Fairy Favour, by by Thomas Hull (1767), Oriel is the fairy prince and heir of Oberon and Titania.
Oberon is descended from the character Alberich.
Ortnit was a German heroes who replaced the mythical Hartnit, one of the Hartung brothers. These heroes were the sons of the Russian hero Ilya Muromets. Hardheri became Wolfdietrich, and more appropriate to this post, Ilya was replaced by Alberich.
Walbert (or Wambert) was eldest son of Alberich the magician in the legendary history of the Merovingian dynasty. (Alberic/Aubert/Auberon is brother to Merowech/Merovee and husband to Lucilla, the daughter or sister of Emperor Zeno. His father was Clodion. In this lineup, Pepin and Charlemagne are Alberic's descendants.)
In the Wagner Dramas, Alberich is the chief of the dwarves and villainous Nibelung who steals the Rhine maidens’ gold, and is the father to Hagen, who murders Siegfried. Hagen’s mother is a human woman named Grimhilde and his half-siblings are Gunther and Gudrun. Here, Auberon's brother is the smith Mime.
There are plenty of modern books featuring children of Oberon and/or Titania; however, the latest one that really fascinates me is Titania's Palace, also known as possibly one of the cutest things I've ever seen.
THIS IS THE MOST AMAZING DOLLHOUSE. The creator was Sir Nevile Wilkinson. The story is that the project was inspired in 1907, when his three-year-old daughter Guendolene said she'd seen a fairy at a nearby tree. This inspired a massive project of an elaborate dollhouse known as Titania's Palace, which took years to complete; it included numerous pieces of artwork, including tiny books with actual writing, and the display opened to the public in 1922.
Wilkinson wrote storybooks for his daughters which mentioned Titania and her prince consort, Oberon; in this private mythology they had seven children. The four girls were Iris (the oldest), Ruby, Daphne and Pearl, and the boys were Zephyr, Noel, and baby Crystal. For these children there were bedrooms and miniature clothes and toys throughout the palace, and even a tiny perambulator.
EDIT: Wilkinson's book Yvette in Venice gives more details on the children. The four daughter all have elemental powers.
Iris (12) is chief of the fairies of the air and whe wears a rainbow around her head.
Zephyr (11) has no information given.
Ruby (9) has the element of fire. Rules over the elves and gnomes who mine precious ores. She has brown hair and hazel eyes.
Daphne (7) is the most social of the princesses and cares for the wood and garden fairies.
Noel (5) is said to help Father Christmas distribute presents.
Pearl (3) is a great swimmer, so presumably affiliated with water fairies.
Crystal (7 months) is said to be a very cheerful baby.
They also have a car, the Grey Fairy, and a Pekingese named Prince Ching.
This website is based on my research into folklore.