Dean Domino

 was a pre-war lounge singer, now ghoulified and trapped in Sierra Madre in 2281.

Background
Prior to the Great War, Domino was a very famous lounge singer, often playing on the old Las Vegas Strip. Although he is a quick thinker, trained with guns (specifically pistols), explosives and knives, he is very paranoid, setting up many booby traps and secret stashes throughout the Villa - perhaps understandably, considering the Ghost People who inhabit it.

After being captured by Father Elijah at the Abandoned BoS Bunker, the Courier must work with Domino to find the treasure at the heart of the Sierra Madre casino and win their freedom. Although he is bound by the collar, Domino possesses his own lust for the treasure he has waited literally hundreds of years for, and will no doubt try anything to obtain it.

Endings

 * If he is rescued by the Courier, then Dean Domino, entertainer, singer... thief... explores the Sierra Madre not long after. Once he leaves the theater, the Sierra Madre recognizes him as a guest, and many doors open to him. He has to admit, it had been built to last. During his search, he comes across the final records of Vera and Sinclair, and realizes what happened the night the bombs fell. He feels strangely sad for a moment, and he has no idea why. Shrugging it off, his mind turns instead to where the Courier had come from. Vegas still survived, out there in the Mojave. Its sights, sounds... and casinos, ripe for the taking. So giving the Sierra Madre one last nod and a wink, he sets off beyond the Cloud to begin again.
 * If he has his last show on the Sierra Madre stage, Dean Domino, entertainer, singer... thief... sees the heist he spent over two hundred years planning fall apart, just as the first, by underestimating his partner's strength. Not long after the Courier leaves the Villa, the lights in the theater shut off, one by one. Only Dean's Hologram remains on stage, singing silently to an empty room. Still... as consumed as he had been with its riches and ruin, the Sierra Madre had held him captive long ago.

Appearances
is mentioned in Fallout: New Vegas and appears in the DLC Dead Money.