Short form of Elizabeth, not used before the 19th century, when it became popular in America and elsewhere after publication of Louisa M. Alcott's novel Little Women (1868), in which Beth March is one of the four sisters who are the central characters.
English and Welsh: patronymic from the Middle English personal name Jon(e) (see John). The surname is especially common in Wales and southern central England. In North America this name has absorbed various cognate and like-sounding surnames from other languages. (For forms, see Hanks and Hodges 1988).