What is it called when your surname is a first name?

When Your Last Name Is Also a First Name

Ever met someone like William Williams or Emma Emmerson and wondered about the quirk behind their name? It’s more common than you might think—and there’s actually a term for it.

While some call it a form of patronymic repetition—where a surname is derived from a father’s first name, such as “Williams” meaning “son of William”—the more precise label is autonymic name. This refers to any instance where a person’s given name and surname are identical or clearly related, either historically or coincidentally.

Names like John Johnson or Sarah Harrison might seem playful today, but they often trace back to naming traditions in English, Scandinavian, and other European cultures. Surnames were once simply built by adding suffixes like “-son” or “-sen” to a father’s first name, so being named after your dad was practical, not whimsical.

Today, these combinations can still carry echoes of that history, even if the connection is no longer obvious. In some cases, it’s purely accidental—a double name born from modern naming trends rather than lineage. But the linguistic charm remains.

So next time you hear Michael Michaels introduced at a meeting, you’ll know it’s not just a tongue twister. It could be a quiet nod to centuries-old naming customs—or simply a happy (or awkward) coincidence. Either way, it’s a small reminder of how language and identity evolve over time.