Cognomen Iolyn (Iolyn 
) , throughout the world, is an extremely rare last name. Much more prevalently, Iolyn is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Iolyn | United Kingdom, United States, Philippines |
| ieuan ab iolyn |
|
|
| efa ferch gwrgeneu ap gruffudd fychan ab iolyn |
|
|
| catrin ferch ieuan fychan ab ab ieuan ab iolyn |
|
|
| ieuan fychan ab ieuan ab iolyn |
|
|
| marged ferch ieuan ap hywel ab iolyn |
|
|
| angharad ferch ieuan ab einion ab iolyn |
|