Probably derived from an old Indo-European root meaning "heavenly, divine", related to dyeus (see Zeus). Diana was a Roman goddess of the moon, hunting, forests, and childbirth, often identified with the Greek goddess Artemis.
As a given name, Diana has been regularly used since the Renaissance. It became more common in the English-speaking world following Sir Walter Scott's novel 'Rob Roy' (1817), which featured a character named Diana Vernon. It also appeared in George Meredith's novel 'Diana of the Crossways' (1885). A notable bearer was Diana Spencer (1961-1997), the Princess of Wales.