What is billy short for?

Billy is a common nickname or short form for the given name William. It is often used as a casual or affectionate way to address someone with the name William. Billy is derived from the Old French name "Guillaume" which means "will, desire" and "helmet, protection."

Famous individuals named Billy or William include actor Billy Crystal, musician Billy Joel, and former US President Bill Clinton, who goes by the nickname Bill which is also short for William.