Great examples! My initial post is far too limited. It fascinates me, though, like etymology does, too.

'Antony' is also related to 'Antonius' (as is 'Italian Antonio').

One weird one (for me) from English is 'William' -> 'Bill' since there's no 'B' in 'William', and no 'W' in 'Bill'. I wonder what's happening there.

Tony is also common in the UK. Anton in parts of South Asia.

Chris can be short for Christian.