In the Middle Ages this name was common in England due to the popularity of medieval tales about the Trojan War. It subsequently became rare, but was revived in the 20th century.
Originally more common as a name for boys in America, it became more popular for girls in the 1960s. It began rapidly increasing after 1973, possibly due to a character (played by Natalie Wood) in the television movie The Affair. It reached an apex in the United States ranked 17th in 1990, though it has quickly fallen away since then.
This name can also be given in reference to the city in Italy, as in the case of Florence Nightingale (1820-1910), who was born there to British parents. She was a nurse in military hospitals during the Crimean War and is usually considered the founder of modern nursing.
As an English name it did not become common until after the Protestant Reformation, despite a handful of early examples during the Middle Ages. It was however used earlier on the European continent, being borne by several European royals, such as the 9th-century Judith of Bavaria.
In the English-speaking world this name has been occasionally given since the early 20th century. It started rising in America after the variant Lorelai was used for the main character (and her daughter, nicknamed Rory) on the television series Gilmore Girls (2000-2007).
In England, it began to be used as a given name after the Protestant Reformation. It was moderately common in the 19th century. It began to rise in popularity again in the late 1980s, probably helped along by characters on the American television shows Friends (1994-2004) and Charmed (1998-2006). It is currently much more common in the United Kingdom, Australia and New Zealand than the United States.
A moon of Saturn bears this name, in honour of the Titan.