Language equivalents and Nicknames

Scots - Ian
Irish (English spelling) - Sean, Shawn
French - Jean
Spanish - Juan
? - Joan (as in Miro)
Italian - Giovanni; Nickname - Gianni
German - Johann, Johannes; Nicknames - Hannes, Hans, Hanschen
Russian - Ivan; Nickname: Vasha
Dutch, Czech, Polish - Jan
Danish? - Jens
Welsh - Evan (Evans is a surname)

English uses Jack for John, although it's use may have come from the French name Jacques or James. Hank may come from German, but if so, just as likely from Heinrich or Henry.