In my country (Spanish speaking) we say "Fulano de tal" Fulano is kinda like a template name nobody really is named like that. "De tal" really means something like "from somewhere".
We dont out it on the graves, but we use it as slang for situations where we need to refer to someone generic like "imagine a fulano de tal doing xxxxxxxxxxx".
There are other names like Zutano, Mengano, etc.
Edit: My mom sometimes uses "Miguel Perez". Those 2 are very common first and last names.