Hologram (Fallout: New Vegas)

Holograms are 3-dimensional projections which sometimes interact with players and non-player characters in Sierra Madre in 2281.

Background
It is believed hologram technology originally stemmed from Stealth Boy research in a scientific drive to match Chinese Stealth Suit technology.

Dead Money
Holograms are present in the Villa, though most are non-hostile and you even have the option to activate several security holograms to guard Dean Domino during the quest Trigger the Gala Event. There is only 1 hostile hologram located in the Villa, it is located inside the Villa Clinic. Holograms are the primary enemy when you first enter the Sierra Madre Casino and you are not able to shut them down due to the Emitters not being accessible, so instead you must use the terminals to reroute their patrols. Later on when you reactivate the power in the casino the security holograms disappear and are replaced with casino floor managers, a Cashier, a Bar tender, and a Lobby Greeter, though if you do not reprogram the Starlet holograms in the Sierra Madre Suite they will attack if you get too close. A hologram of Dean Domino can also be used to shut down the Security protocols in the Tampico Theater. Holograms are also present in Sierra Madre vault in the last room before you enter the Vault itself.

Old World Blues
Two holograms appears in Old World Blues in Z-38 lightwave dynamics research. The player cannot interact with them and it was probably a prototype or a test subject for the scientists.

Hologram
This version of the hologram is the main security version. They appear in the Villa Clinic and in the Sierra Madre Casino. It appears to be wearing Sierra Madre security armor. The emergency defense system activated these holograms when the bombs dropped, and they are still actively patrolling. It best to avoid being seen by these holograms, or to find their emitters and disable them. The security holograms can disguise themselves as other holograms so watch out.

Starlet hologram
The starlet holograms all have the appearance of Vera Keyes. Unlike security holograms, Vera Keyes holograms don't always attack the player, the exceptions being the hologram in Vera's room, and the Executive Suites. Outside the Sierra Madre Casino there's an additional starlet hologram, featured very prominently, in the central non-functioning Villa fountain.

Hologram vendor
Throughout the Sierra Madre there are several vendors from which to buy various items, such as food and drinks. Vendor locations include the casino, and the cafe. This type of hologram will ignore attacks, and will not turn hostile towards the player character.

Although they have no caps (being pre-War tech), the vendors carry large quantities of pre-War money which you can use to barter with them.

Dean hologram
Dean hologram is a stage-performing hologram found in The Tampico theater at the Sierra Madre Casino. During the quest Curtain Call at the Tampico, the hologram of Dean Domino will perform the song "Something's Gotta Give", on the Tampico stage. After the song, he will receive some applause from hologram spectators, and subsequently disappear from the stage.