If you meet one of these two conditions, you can apply online for Irish citizenship. Expect a fee of 278 euros (about $330) if you’re at least 18 years old, or 153 euros (about $180) if you’re younger. You’ll also have to provide several documents, a list of which includes your Irish parent or grandparent’s original birth certificate, your own birth certificate, and two proofs of address.
If one of your parents was born in Ireland and is an Irish citizen, you’re already considered an Irish citizen and can simply apply for a passport.
Italy
Italy’s “citizenship jure sanguinis,” or citizenship by descent law, applies to applicants with a parent or grandparent who was an Italian citizen (with no other citizenship) at the time of their death. You also qualify if your parent was/is an Italian citizen and lived in the country for at least two consecutive years before you were born (or adopted).
If you fit the bill, you can apply via a virtual appointment. Be sure to come prepared with the $697 fee and the required—and highly specific—set of documents, which include the Italian relative’s birth certificate (issued within the last half-year by the commune where the person was born) and the birth certificates of all direct descendants, including your own (“in long form, duly legalized, and translated into Italian”).
If your relative moved out of Italy, you’ll need to provide documentation showing they didn’t acquire citizenship in a foreign country. If they did naturalize, you’ll need to send a notarized copy of their naturalization certificate.
Portugal
You can obtain Portuguese citizenship if one of your parents is a Portuguese citizen, or if one of your grandparents is or was Portuguese and you know the language (as certified by an official language test).