Fallout 3 random encounters

Throughout the world of Fallout 3, you can encounter random events in the Wastelands. There are certain places where random encounters can happen, but once "activated", a random encounter in a particular area won't change.

You can save outside the spawning area and keep reloading if you don't get the encounter you want.

Random Encounter Locations
These are the known locations so far:

Special/unique npc encounters

 * Amata being questioned by two hostile Enclave soldiers and a non hostile Enclave officer; if you talk to her, move too close to the soldiers, let the soldiers finish talking to her, or attack the soldiers, Amata will be killed; you can save her for no reward or dialog options, she will only say this is all your fault, even if you convinced her that her father/the new Overseer destroyed the Vault.
 * Ben Canning. He is dying of thirst and asks for Purified Water.
 * Dogmeat might appear, if you have not recruited him yet.
 * Donovan from Reilly's Rangers who will give you a Mini Nuke if you completed Reilly's Rangers.
 * Laszlo Radford, hostile and will open fire on you with his Railway Rifle.
 * Mel, a modern Highwayman who will demand caps and items from you. You can either utilize speech options, or kill him.
 * Sam Warrick shooting at a Wastelander (if he kills the Wastelander, he'll turn on you).
 * Susie Mack, if you made Amata the Overseer of Vault 101 during Trouble on the Homefront. She will tell you that the Vault is doing fine and give you Purified Water.
 * Uncle Leo, a friendly Super Mutant. If you tell him you're going to rob him, he'll give you a Dirty Pre-War Businesswear as a present. If you attack him he'll run away instead of fighting.


 * "Wasteland Doctor", a Doctor/Merchant that can heal you and/or sell you medicine.
 * "Wasteland Junkie", a Merchant that can sell you drugs.
 * "Wasteland Merchant". After having a talk with him about the Great One, he'll collapse and die.  You'll find a Wasteland Merchant Note on his body about him going to Oasis the next day.

Hitmen, Regulators and angry mobs

 * A Talon Company ambush if you have a Karma rating of Good, with the "Private Contract" note.
 * A Regulator ambush if you have a Karma rating of Evil. Sometimes there is a Speech challenge where you can bypass them.
 * A Hitman ambush, with the "Contract for Extermination" note, Karma independent.
 * Four Slavers seeking to eliminate you as competition because you have made them look bad - if you capture a large amount of slaves.
 * Three Megaton refugees who attack you with knives (available if Megaton is destroyed)

Scavenger encounters

 * A Scavenger with one or more of the following pets: a Brahmin, Dog or trained Yao Guai. He'll offer you a Nuka-Cola Quantum.  You can barter with him into reducing the price.
 * The Scavenger might also appear without pets, and might be dead, too.
 * A Scavenger and his dog or Yao Guai fighting a Protectron, Robobrain or Super Mutant. If you go near the Protectron/Robobrain/Super Mutant after you kill it and the Scavenger is still alive, he'll tell you to stay away from his loot and may attack if you persist on "stealing" from him. If that's the case, killing him results in negative karma.
 * A Scavenger with his malfunctioned Mister Handy. If you repair it, the Scavenger will give you two Energy Cells.  With a speech check, you can convince him to give you 100 caps and the energy cells.
 * A Scavenger and his dog or a trained Yao Guai. He will tell you that Big Town has made a large order for guns, and he is headed there. You can trade with him, he carries a number of weapons and ammo. This encounter only appears after completing the quest Big Trouble in Big Town, with the "guns" option rather than the "robots" option.
 * A Scavenger that tells you "I'm going to Big Town, there's a lot of money to be made there. They ordered a bunch of robot parts." You can tell him you could use some robot parts to trade with him. He has no robot parts or scrap metal, but does have some ammo, weak melee weapons, and useless junk. You can ask him to repair your stuff, repair everything, then kill him for your caps back along with whatever he had for sale. This will result in negative karma. He can only be seen after completing Big Trouble in Big Town with the robots option rather than the guns option.
 * A dead Scavenger holding a Fat Man in good condition and a Mini Nuke.

Wastelander/Slaver/Slaves encounters

 * Two Wasteland Settlers and two Escaped Slaves fighting over a refrigerator of 10 Purified Water.
 * Two Wastelanders pondering an Enclave Eyebot that hovers around them consistently (as opposed to a long patrol like most).
 * Ghoul Wastelanders around a burning barrel, telling you they were headed for Underworld but couldn't make it because of Super Mutants.
 * A Wastelander killing and looting a Mole Rat (only after completing the Wasteland Survival Guide quest). He has different dialogue options, depending on whether or not the player completed all bonus objectives given by  Moira. If the player says he has helped with the book, a congratulatory or a mocking response is received. If the player says he has never heard of the guide, the Wastelander will provide him with a copy of the book.
 * Three Slavers with three Slaves.
 * Two to Three Wastelanders fighting a Deathclaw. (Note that the Wastelanders DO NOT have the schematics for a Deathclaw Gauntlet, see below.)
 * Three Wastelanders with the location of the Oasis. If you approach and talk them they turn hostile for mistakenly revealing the location of the  Oasis.
 * A Wastelander attacked by Mole Rats. If you save her she'll give you a small amount of caps.
 * A Wastelander attacked by Radscorpions.
 * Two Wastelanders fighting a Giant Radscorpion over a fridge of 8 purified water.
 * A Wastelander or Slaver fighting Vicious Dogs.
 * Three Wastelanders fighting with a Deathclaw. If you save them they'll give you the location of Rock Creek Caverns.
 * Two or three Ghoul Wastelanders in a stand-off with two or three Wastelanders or Escaped Slaves over a fridge full of purified water. You will get half of the water for helping one side to kill the other.  If you arrive after one side has already been killed (usually the non-ghouls), you can also attempt a Speech check to take half of the water.
 * A few Escaped Slaves who have a few dialogue options if you talk with them: if you know where the Temple of the Union is, you can give them the correct directions for some positive Karma, or lie to them for negative Karma, or just say goodbye.
 * A Wastelander runs up and tells you Grayditch is burning. (Reveals location of Grayditch)
 * Two Wastelanders near Frag Mines; one Wastelander will unsuccessfully try to disarm one of the mines.
 * Four escaped slaves who will ask you to remove their collars. Depending on your science skill, you could take it off for positive karma, or it could make their head explode.

Hunters

 * Three Hunters.
 * A lone Hunter selling meat.
 * 2-3 Hunters attacking a Giant Worker Ant or Giant Soldier Ant.
 * Three Hunters attacking a Vicious Dog.
 * One or two Hunters fighting a Yao Guai.
 * Three Hunters chasing and attacking a Wastelander. Killing the hunters results in positive Karma, and they carry Strange Meat, indicating they are roaming cannibals

Raiders and Slavers

 * Five Raiders, four beating the fifth one, who is in undergarments, from all sides, in turns. It seems to be an initiation.
 * Three Raiders and a Wastelander with a time-bomb on him. (Bug: see Wastelander.)
 * Two Raiders fighting two Eyebots. The Eyebots usually win.
 * Two Slavers who will shoot you if you fail the Speech challenge.
 * A single Raider fighting Vicious Dogs.
 * 1-3 Raiders attacking 1-3 Wasteland Settlers.

Corpse encounters (with or without animals/monsters)

 * A Deathclaw and a dead Wastelander. You can find the schematic for the Deathclaw Gauntlet on the dead Wastelander.  (It is possible to save him; dialog will get you the schematics and a location marked on your map where he was attempting to go.)
 * 1-3 Vicious Dogs and a dead Wastelander. Wastelander's body has John's Key and a Wastelander Note which starts you on the John's Treasure Box unmarked quest. (Bug: The wastelander does not always appear dead.)
 * Dead Vault 101 dwellers and a Giant Radscorpion - if you drove the Vault 101 dwellers out of the Vault.

Exceptional monster encounters

 * A Deathclaw surrounded by the bodies of various robots, wasteland creatures, raiders, slavers and wastelanders.
 * If you receive a Chinese Radio Beacon over your Pip-Boy you'll find a Dead Chinese Commando at the spawning point.
 * A giant Radscorpion fighting 1-4 Giant Worker Ants
 * A random number (up to four) of Mad Brahmin.
 * One to four Giant Ants around a toxic barrel with one being bigger than the others.
 * 5-7 Radroaches.

Brotherhood Outcasts

 * One Brotherhood Outcast Robobrain.
 * Two Brotherhood Outcasts and a Protectron.
 * Two Brotherhood Outcasts with a Robobrain.
 * Two Brotherhood Outcasts with a Robobrain fighting a small group of Enclave Soldiers.
 * Two Brotherhood Outcasts armed with a Laser Rifle and Missile Launcher fighting two Yao Guai.
 * Three Brotherhood Outcasts. Two with Laser Rifles and one with a Gatling Laser.
 * Three Brotherhood Outcasts armed with Power Fists.
 * Three Brotherhood Outcasts fighting a Deathclaw.
 * A small squad of Brotherhood Outcasts being chased by two Deathclaws.

Item encounters

 * Four Frag Mines scattered with no one around.
 * A UFO exploding overhead, dropping Firelance and spilling exactly 24 Alien Power Cells all over the area. It helps to have Dogmeat search for the remaining ammo if you can't find it.  Also, if you get this encounter to spawn near a building like the Super-Duper Mart, it's possible the ammo or the gun will clip through the building.  The only way to get the ammo is to have Dogmeat search for the ammo or gun, then when he is running up against the structure you can push him through it.

Other

 * Two Protectrons dueling.
 * A Vertibird getting hit by a missile and crashing near you.
 * A Vertibird landing, dropping off a combination of Enclave soldiers and/or Sentry Bots, and then flying away. (Unless you shoot it down, first.)