A word for a "non-logged in" user

On my website, I allow the user to create a document - but if they aren't logged in, then the document will not have an owner and therefore be editable by anyone.

I want to display a warning for any documents that are editable by anyone to explain that the document was created by a "non-logged in" user and that if they want to restrict access, they should log in and claim the document as theirs.

What is a better term than "non-logged in user"?

A better term would be an anonymous user, as you do not know the identity of the user.

Such users are usually called guest users.

Update: To conclude this long discussion, I think we should take a closer look at what others (specifically, key players) call such users. This helps us to provide users with an acceptable and familiar user experience, at least in nomenclature.

Let's take a look at what is common in the real world:

docs.Oracle : "* When a user visits your portal without logging in, that user is called "anonymous." While working with anonymous users is inherently limiting in some ways (because there are few things you know for sure about them).*"
"Guests are anonymous users who have not registered and have not logged in."

Wikipedia: "Anonymous users (those known only by an IP address) cannot edit their own user pages until a logged-in user begins it, or they log in (or sign up) themselves."

documentation.bonitasoft : "An anonymous user is a user who does not need to log in to Bonita BPM before accessing a process form. An anonymous user is always be the initiator of a process."

help.sap: "This function enables Web shop customers to create orders in the Web shop without registering a user name. In the back end, the data guest users enter is only saved with the order; there is no master record created. This is why the My Account functionality is not available to guest users."

support.office : "Guest users, also called anonymous users, don’t need a Microsoft account or work or school account to access documents. They access the document via a guest link that you or your employees give to them."

All in all, it seems that anonymous and guest can be used interchangeably, however calling such users anonymous implies a negative connotation, IMO. So I do recommend to call them in a more respectful way by using guest.

Specifically when referring to users who have not logged in, in my company, we call them unauthenticated.

un·au·then·ti·cat·ed: adjective. not proven or validated.

- Source (Google)

Maybe incognito, lurker, or unknown. It all depends on how formal of a word you need.