Hercules
There is no specific myth or reasoning behind the use of the number 12 on mythology aside from it's connection to the calendar and the zodiac. The only instances of 12 are the 12 Olympians and the 12 labors of Heracles (which were originally 10)
To perform his 12 labors.
The hero who performed the 12 labors was Heracles, known as Hercules in Roman mythology. He was tasked with these labors as a form of penance for killing his family in a fit of madness, which had been inflicted upon him by the goddess Hera. The labors included challenges such as slaying the Nemean Lion and capturing the Golden Hind of Artemis, showcasing his strength and bravery. Ultimately, these feats solidified his status as one of the greatest heroes in Greek mythology.
Heracles (Greek) Hercules (Roman) had to complete 12 labors.
Hercules
According to Greek mythology, Hippolyta was the queen of the Amazons - who were women warriors. She mainly shows up in the mythology in relation to Hercules/Heracles getting her girdle (a gift from her father, the God Ares) as the ninth of his 12 labors and in a variety of myths that had her married to Theseus.
Hercules
By carrying out his 12 labors.
Perseus. Bellerophon killed the Chimera, Theseus killed the Minotaur, and Heracles completed the 12 labors.
Herakles AKA Hercules.
Heracles, also known as Hercules in Roman mythology, performed the 12 labors. These labors were tasks that were assigned to him as penance for killing his family in a fit of madness induced by Hera, Zeus's wife. Heracles successfully completed all 12 labors, showcasing his immense strength and courage.
Hercules because he wanted to