The Great Cow of the Arch of the Sky
This is the formal throne-room title of Queen Artela of Djelibeybi.
She was the wife of Pharoah Teppicymon XXVII and, after the mandatory servicing, the mother of Pteppicymon XXVIII. She was just about the only battle that Teppicymon XXVII won against his overpowering steward and chief priest Dios, who protested strenuously about the impure foreign strain she was bringing into the royal family. Her country of origin is not recorded, but some of her quaint foreign ways, such as a dislike for pyramids, had puzzled and fascinated even her husband, who was sure he'd got his own post-mortem pyramidophobia from her.
She didn't just worship cats (as was mandatory in Djelibeybi). Instead, she liked them, even the flat-headed yellow-eyed screaming maniacs.
Dios always knew she was going to be trouble. She and her brother Vyrt conspired to ensure that young Teppic was sent away from the Djel for his education - the Assassins' School in faraway Ankh-Morpork, to be exact.
It is a telling detail that shortly after the succession was ensured, she went for a midnight swim, hitherto unheard of in Djelibeybi, only to encounter the large, scaly, and above all sacred, reasons why nobody in the country knows how to swim.
Her epitaph might be People never learn anything in this place. They only remember things.
She was remembered by her son as a pleasant woman who was as self-centred as a gyroscope.
The Discworld Zodiac has a constellation and sign simply called the Cow of Heaven. The two concepts may be related, as so much of the zodiac, according to the The Compleat Discworld Atlas, is the creation of Central Sea peoples living into deserts who were starved of entertainment and things to look at other than sand-dunes and palm trees.
Annotation
It has been suggested that the parents of Pteppic are a direct and deliberate parallel of the central characters in Mervyn Peake's Gormenghast trilogy. The setting is a several-thousand-year-old state (Djelibeybi/Gormenghast) which has fossilised into a tyrannical regime of age-old rituals which nobody dares to question the modern significance or relevance of; the Rituals are ferociously guarded and imposed by a fossilised Loremaster who embodies the tradition of the state in his own being (Barquentine/Dios). Most of the free income goes into endlessly maintaining old structures or building new ones to the same pattern (Pyramids). The ruling family consists of a rather vague and introspective Count/Pharoah, married to a woman working on instinct who loves cats (the Countess/Artela). In his death throes, the Count of Gormenghast hallucinates that he is an owl. Teppic's father has the same delusion about a seagull.
Of their children, the son (Titus Groan/Pteppic) goes out into a world not ruled by tradition and groaning under the weight of the past to see how things are done elsewhere, specifically in a fairly nearby but unspecified Big City. The daughter (Fuchsia/Ptraci) is also intensely dissatisfied with her lot and, if given a chance, would try to change it for the better - in Pyramids, she manages it, in Gormenghast, she dies in ambiguous circumstances. Pteppic is also an archetype of anti-hero Steerpike, in that he climbs to the highest point in the Kingdom and brings about its dissolution (Steerpike dies trying in Gormenghast, but at this point, he has mutated into an embittered scarred and burnt villain who, interestingly enough, conceals a mutilated face behind a mask... another Roundworld fable creeping in here?)
On swimming in the Djel: the former BBC radio presenter Sarah Kennedy, a woman who frequently went her own eccentric way and got into trouble for it with BBC bosses, once advanced a theory about athletes of African origin. This was shortly after a Central African olympic competitor got into the history books ever for the longest, slowest, most laboured, 400 metres in a top swimming competition. When all seven other swimmers had finished, towelled down and in some cases showered and got dressed, he was still in the pool finishing his heat. The delightful Sarah then advanced a theory as to why so many Africans are world-class runners - "lions" - whilst you never see a black African winning a swimming event - "crocodiles". She was immediately suspended for making non-politically correct comment...