This is not exhaustive. I checked name frequency tables in different languages, and some that aren't common or notable enough aren't listed. Hope you have fun.
Advice for the Welsh answer (and possible type-ins): 'Sion' is a more common form of John in Welsh (along with Ioan, Ieuan, and Ifan) - Evan is actually Anglo-Welsh, as the letter 'v' isn't in the Welsh alphabet, so I'd recommend using Sion instead or at least accepting it as a type-in :)
It's also the Welsh name for Father Christmas (Sion Corn, or John Chimney)!
It's also the Welsh name for Father Christmas (Sion Corn, or John Chimney)!