Gary (clone)

Gary was one of the original inhabitants of Vault 108, and clones of him are the only people left in the vault by 2277. The clones are all numbered and all of them are hostile towards non-clones.

A holodisc found in the Vault 108 cloning lab explains that Gary was cloned at least 54 times; all clones exhibited hostility towards non-clones, with each successive clone being more and more violent. When the Vault scientists started running out of room to store the clones, they planned to destroy some of them to make room for additional test subjects. Apparently, the clones objected to this, escaped, and slaughtered the rest of the Vault's inhabitants.

The clones usually only speak their own name, using different tones to express anger, curiosity, or pain. However, the Gary's do seem capable of saying at least a few other words: "Hey", "Hello", "Watch Out", "Evening", "No," and "Haha".

All of the Gary clones wear Vault 108 Jumpsuits. With the exceptions of Gary 1 and Gary 25, who carry N99 10mm Pistols, and Gary 27, who carries an AEP7 Laser Pistol, all the clones use melee weapons such as knives or lead pipes - although they will pick up better weapons from their surroundings, if possible. Notably, Gary 1 is only carrying 9 rounds of ammunition even though a 10mm Pistol has a 12 round magazine, indicating possible suicide by gunshot. There is also a random occurrence where Gary 47 will be equipped with a Scoped .44 Magnum. This is akin to the clone Agent 47 of the Hitman.

Overall, the Gary clones are rather weak, and can easily be dispatched by a single Hunting Rifle headshot or 2-3 pistol headshots.

Note
Answer: Perhaps this one Gary escaped and was wandering the wastes when they found him.
 * In the Outcast Outpost (from the Operation: Anchorage DLC), a dead Gary 23 can be found wearing a Vault 108 jumpsuit in the locked room across from Protector McGraw. The room has an easy lockpick skill so it will not be hard to get in. Gary 23 has nothing on him and his jumpsuit cannot be removed. If you inspect his body and the surrounding area, you will notice that his left arm has been cut off and that there are a bunch of medical tools nearby (ie: 2 bonesaws, knife, scissors). After listening to Protector McGraw, you can assume that the Outcasts tried to get the Pipboy off of him by cutting his arm off. Whether he was killed by them, his body dragged there, or killed in the simulation, is not certain, but the first scenario is more likely, due to the pool of blood.  However, Specialist Olin comments on how it wasn't her fault 'what happened to the first guy'. Seeing that they ask you for your help, you can also assume that Gary 23's Pipboy did not work, or they screwed it up in the process. This situation creates a strange question: where did they find Gary 23, and if they found him with the other clones, why not capture more?
 * The fact that the Garys' can only speak their name could be reference to the South Park character Timmy, who is almost only capable of saying "Timmy!" in different tones.