What's your name?

Like many languages Greek has a familiar way of introducing yourself and more formal versions. The familiar is shown in this short conversation between Nikos and Kostas:
Κώστας: Πώς σε λένε; What's your name?
Νίκος: Με λένε Νίκο. Εσένα; My name is Niko. And you?
Κώστας: Με λένε Κώστα. My name is Kosta.

In uppercase those phrases are:

NB the semi colon (;) symbol is used in Greek as a question mark.

More formal ways of asking, "what's your name?" are:

ΤΟ ΟΝΟΜΑ ΣΑΣ; το ονόμα σας;
ΠΟΣ ΛΕΓΕΣΤΕ; πος λεγεστε;

and reply "my name is" with:
ΤΟ ΟΝΟΜΑ ΜΟΥ ΕΙΝΑΙ το ονομα μου ειναι
ΟΝΟΜΑΖΟΜΑΙ ονομαζομαι
ΛΕΓΟΜΑΙ λεγομαι

And the slightly more formal way to say "and you?" is to add the and in so "ΕΣΕΝΑ" (literally meaning just "You?") becomes "ΚΑΙ ΕΣΕΝΑ;"

To use Mr and Mrs use ΚΥΡΙΟΣ (κύριος) for Mr and ΚΥΡΙΑ (κυρία) for Mrs, so you would say:
Με λένε ο κυρίοσ ....... / My name is Mr ....... or
Με λένε η κυρία ........ / My name is Mrs .......