Usually they are known by that title and "the cat" tells you something more about them. Not just any cat, but a specific one. Here are some examples children know of: Felix the cat Barney the dinosaur Dora the explorer Bob the builder Thomas the train etc. If I merely said Bob or Thomas, you may wonder who I am referring to. In reference to your example of Julia, there is a case where you might say that. Imagine you are telling me about "Julia" but we know more than one Julia so to clarify I ask "Julia the hairdresser?" and you say "No, Julia the teacher". If it's a common name, I'm more likely to mention their profession or a similar reference that helps identify them. Now maybe Julia does lessons on YouTube and rises to fame and becomes known internationally as "Julia the teacher". It could happen someday. ;) -Shawn the polyglot

In this case it's almost like saying "Felix, not the person, but the cat." You can say, "Julia the teacher" but only when we don't know which Julia someone is talking about. Like so: - Which Julia are you talking about? Julia the doctor? - No, Julia the teacher. The usage of "Felix the cat" is typically for mascots and kids shows. It's almost funny. That's about the best I can describe why we do this.

This is hard. Shawn & Drew are right that you can use name+the+noun to indicate which Julia or Bob or Thomas you're referring to. However in some cases, it is better to think of Name+the+Noun as that person or character or thing's name. Felix the Cat is one of those. He isn't "Felix" he's "Felix the Cat" and has been for almost 100 years. Those three words together are his name. (A more modern example is "Chance the Rapper." If you look he's almost never referred to as "Chance." He's "Chance the Rapper.") If you want to use it in that way, you'd need to pick a noun and then never not use it. Every time you talk about that person, you would need to say name+the+noun so that when someone thinks of that person, they think of them as name+the+noun.

Hey there, "The" in this context is basically just used to introduce the subject that you're talking about. E.g.: His name is Felix, he is a cat. He is "Felix the Cat." That works with other subjects and names as well, for example: "Julia the teacher", or " Jack the father". It's really just a small detail you don't have to worry about much. Hope I could help.