The given name Billie has its origins in the Germanic languages, deriving from the Old English word "bili," which means "benevolent" or "kind." It emerged as a diminutive form of the masculine name William, which itself is derived from the Germanic compound name "Willahelm," meaning "will" and "helmet."

In the Middle Ages, Billie was a common nickname for William, particularly in England and other parts of the British Isles. The earliest recorded use of the name Billie as a standalone given name dates back to the late 16th century, when it began to be used for both boys and girls.

One of the earliest notable individuals with the name Billie was Billie Frecheville, an English noblewoman who lived in the late 16th and early 17th centuries. Another early figure was Billie Belasyse, an English politician and Member of Parliament in the mid-17th century.

In the 19th century, the name Billie gained popularity, especially as a feminine name. One of the most famous individuals with this name was Billie Holiday, the legendary American jazz singer and songwriter (1915-1959), whose real name was Eleanora Fagan.

Another notable Billie was Billie Jean King, the American former World No. 1 professional tennis player and pioneer for gender equality in sports (born 1943). Other famous Billies include Billie Piper, the English singer and actress (born 1982), and Billie Eilish, the American singer-songwriter (born 2001).

Throughout its history, the name Billie has been associated with a sense of warmth, kindness, and a down-to-earth nature, reflecting its origins in the Old English word "bili." While it has undergone various spelling variations, such as Billy, Billee, and Billi, the name Billie has endured as a beloved and widely recognized given name across numerous cultures and generations.