Billie is a gender-neutral name of English origin, derived from the French name William, which means "resolute protection." The name Billie has been used as a unisex given name for centuries but gained significant popularity in the early to mid-20th century. It was often used as a nickname for both boys and girls named after William or Wilhelmina. Today, Billie is still employed as a given name but has also become popular as a surname in English-speaking countries. Some famous individuals with the name Billie include Billie Holiday, an influential jazz singer from the 1930s and 40s, and Billie Jean King, a renowned tennis player who won 39 Grand Slam titles during her career.
The name Billie experienced significant popularity fluctuations over time. From 1880 to around 1925, there was a steady increase in its usage, peaking with 1320 births in 1927. However, it began declining thereafter, dropping from 1474 births in 1930 to just 6 births in 2021 and 7 in 2022. The total number of births recorded for the name Billie over this period is 31,614.