Names and titles are used both when talking about people and when talking to them.

Talking about people
We can name people in four ways.

Using the first name
This is very informal. To talk about our relatives, close friends and children, we usually use the first name.

Where is Peter?
Jane phoned in the morning.
Did you know? Jack is getting married.

Using first name + surname
This style is neither particularly formal nor particularly informal.

I like Brad Pitt the actor.
Mark Twain is my favorite writer.

Using title + surname
This style is more formal. It is used when we talk about people we don’t know, or when we want to show respect.

Could I meet Mr Lewis, please?
We have got a new music teacher called Mrs Sanders.

Note that we do not usually use title + first name + surname to talk about people.

Call Ms Sanders. (More common than ‘Call Ms Mary Sanders’)

Using only surname
This style is used when we are talking about public figures like politicians, writers, actors, sportsmen etc.

I think Shaw was one of the best dramatists of his time.
Have you read anything by Dickens?