It started with Yochanan (Hebrew) -> Ioannis (Greek) -> Johannes (Mediaeval Latin) -> Jon (Middle English), but now every language seems to have a version, e.g.
Hans
Joanna
Hanna
Jan
Ivan/Ivanka
Vanja
Jens
Sean/Shaun/Shawn/Shane
Joan/Jane/Jean/Janis
Evan/Ewan
Jock/Jack
Ian/Iain/Ianto
Juan
Yiannis/Gianna
Gianni/Giovanni/Vanni/Giovanna
Jonas
Ivo/Iva
Eoin/Owen
Seonaid/Siubhan
and those are just the ones I've heard used, there are hundreds more!