Omertas

The  is a faction that controls a section of New Vegas.

Background
The Omertas are a somewhat shadowy faction who control the Gomorrah casino who are based on the Mafia. Prior to being recruited by Mr. House they were known as the "Slither Kin" - a nomadic tribe infamous for luring victims into their camps before murdering or enslaving them; a viciousness that appealled to House, reminding him of certain criminal elements that once operated in Las Vegas.

Interactions with the player character
The way to come across the Omertas is through the main storyline. For various organizations you are asked to get in contact with the Omertas at some point. You start out a quest with them when you're asking around to know what the family has been up to. A member of the family comes up and asks why you've been asking questions about them. To get info out of him you must enter his room and steal his diary from his desk, or pickpocket him. At this point there are many ways to go about this so no need to explain in great detail. After you finish the quest the Omertas should Idolize you in the General section on your Pip-boy.

Appearances
The appear in Fallout: New Vegas.

Behind the Scenes
Omerta is the code of silence in Sicillian/Italian organized crime organizations.

The name of the casino Gomorrah is most likely a reference to Camorra, a mafia like crime organization in Italy.

Trivia
The player may hear Omertas talking about a "Mr.Not-at-Home", this is their nickname for Mr.House.