Apollo is the ancient Greek and Roman god of music, sunlight, poetry, art, and knowledge. He is the son of Zeus and Leto, and the twin brother of Artemis/Diana; Apollo is the father of Asklepios, the god of healing, and thus the grandfather of Hygieia. He is also regarded as one of the Twelve Gods, the major deities of the Greek pantheon.
According to Greek myths, Apollo and his sister were born on Mount Kynthos on the island of Delos. Due to this, Delos was regarded as the island of Apollo.
Apollo came to be regarded as the "divine protector" of the island of Keos, though he was worshipped throughout the Greek world in various roles.
"The people honor the shining one, son of Leto, brother of Artemis, bringer of the sun, Delos' fair Hunter, God of the Lyre, Apollo. It is for him that this city is founded. In his name, in his great and worthy shadow, in his grace, in his light."
When the Greeks founded the colony of Cyrenaica in Africa, they brought the worship of Apollo along, building a temple complex in the city of Cyrene. By the 1st century BCE, Apollo was still widely worshipped by ancient Greeks, who regarded him as the patron god of the city.