From Old French Jo(h)anne, and so a doublet of Joan. This too was revived as a given name in its own right in the first half of the 20th century. It has to some extent been influenced by the independently formed combination Jo Anne.
Italian and Spanish: from the personal name Marcello, Latin Marcellus, a diminutive of Marcus (see Mark 1). This was borne by a large number of minor early saints, and consequently became popular as a personal name during the Middle Ages.