The name Cynthia has its origins in ancient Greek mythology. It is derived from the name Kynthia, an epithet of the Greek goddess of the moon, Artemis. The epithet stems from Mount Kynthos on the island of Delos, where Artemis was born and had a sanctuary.

Cynthia was a relatively common name among the ancient Greeks, particularly in the region of Delos and the surrounding islands. It is believed to have been first used as a personal name around the 5th century BC.

One of the earliest recorded instances of the name Cynthia can be found in the works of the Roman poet Propertius, who lived from around 50 BC to 15 BC. In his elegies, he addresses his beloved as Cynthia, though it is unclear whether this was her real name or a poetic pseudonym.

Another notable figure in history bearing the name Cynthia was Cynthia Longinus, a 2nd century AD Greek philosopher and teacher of Neoplatonism. She was highly respected in her time and is said to have taught the renowned philosopher Porphyry.

During the Renaissance, the name Cynthia gained popularity among the nobility and upper classes in Europe. One notable figure from this era was Cynthia Vendramin, a 15th-century Italian noblewoman and patron of the arts, known for her beauty and intelligence.

In the 17th century, the English poet Michael Drayton wrote a collection of poems titled "Endimion and Phoebe," in which he refers to the moon goddess as Cynthia. This further popularized the name in English literature.

Another famous Cynthia in history was Cynthia of Brandenburg (1573-1625), a German princess and Duchess of Saxe-Lauenburg. She was known for her intelligence and played a significant role in the politics of her time.

In more recent centuries, the name Cynthia has continued to be used, though its popularity has waxed and waned. Some notable figures include Cynthia Ozick (born 1928), an American novelist and essayist, and Cynthia Lennon (1939-2015), the first wife of John Lennon of the Beatles.