Niobe
Niobe, a queen of Thebes and wife of Amphion, boasted of her superiority to Leto because she had fourteen children (Niobids), seven sons and seven daughters, while Leto had only two. For her hubris, Apollo killed her sons as they practiced athletics, and Artemis her daughters. Apollo and Artemis used poisoned arrows to kill them, though according to some versions a number of the Niobids were spared (Chloris, usually). Amphion, at the sight of his dead sons, either killed himself or was killed by Zeus after swearing revenge. A devastated Niobe fled to Mount Sipylus in Asia Minor and either turned to stone as she wept or killed herself. Her tears formed the river Achelous. Zeus had turned all the people of Thebes to stone so no one buried the Niobids until the ninth day after their death, when the gods themselves entombed them.
The Niobe narrative appears in Ovid's Metamorphoses, (Book VI) where Latona (Leto) has demanded the women of Thebes to go to her temple and burn incense. Niobe, queen of Thebes, enters in the midst of the worship and insults the goddess, claiming that having beauty, better parentage and more children than Latona, she is more fit to be worshipped than the goddess. To punish this insolence, Latona begs Apollo and Artemis to avenge her against Niobe and to uphold her honor. Obedient to their mother, the twins slay Niobe's seven sons and seven daughters, leaving her childless, and her husband Amphion kills himself. Niobe is unable to move from grief and seemingly turns to marble, though she continues to weep, and her body is transported to a high mountain peak in her native land.
Read more about this topic: Leto