Giovanni
The Italian derivative of the latin name Johannes is said to come from the Greek name 'Ioannes' which was an adaption of the Hebrew name 'Yochanan' or 'Yahweh' meaning 'Gracious' or 'God is Gracious'. The English equivalent of this popular name, is John.
Spelling variations include: Giovani and Givanni although these are most likely mis-spellings rather than alternatives. The first and middle names were often written or spoken using a shorthand form of the two names, so 'Giobatta', 'Giambattista' or similar would be read as 'Giovanni Battista'.
See also Battista.
This is quite important to note as the English documentation for Italian migrants sometimes only contains the shorthand version, a nickname or the most commonly used name instead of the full name given at birth.
George / Georgette
Greek origins, meaning 'A Tiller of the Soil' or a farmer. Georgette is the feminine form of George.
Gina
Shorthand form of Georgina (see George above) or Regina, of Latin origin meaning Queen.
Giorallmo
Italian origin, meaning ?.
Gordon
English origin, meaning 'From the cornered hill'.
Grazia
Italian origin, meaning 'Grace'.
Guerino
Italian origin, meaning ?.
Guillermo
Italian origin, meaning ?.
Gwen or Gwendoline
Celtic and Welsh origins, with several variations in spelling and meanings. Gwen means 'fair, white', Gwenddydd means 'fair day' (in legend, the sister of Merlin), Gwendolyn, Gwendoline and Gwennor are forms of Gwenhwyfar which means 'fair spirit', Gwenllian means 'fair flood'