Omertas

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

Background
The Omertas control the Gomorrah casino, which is located on the New Vegas Strip, just across from the Lucky 38. They present themselves as stereotypical conceptions of the Sicilian Mafia and the American Mafia.

Prior to being recruited by Mr. House, the Omertas were a wasteland tribe known as the "Slither Kin" - a tribe grown infamous for the practice of luring unsuspecting victims into their camps before murdering or enslaving them. Some sources suggest that the viciousness of the Slither Kin appealed to Mr. House by reminding him of certain criminal elements that once operated in (old) 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 several ways to proceed (see side quest: How Little We Know).

Appearances
The appear in Fallout: New Vegas.

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