|For the character, see Mysterious Stranger (character).|
Fallout and Fallout 2
The Mysterious Stranger will occasionally lend a hand in hostile random encounters. They can appear as either female or male, depending on the player character's sex.
Fallout 3 and Fallout: New Vegas
The Mysterious Stranger has a 10% chance to appear when using V.A.T.S, and is exclusively male in both games, as well as any subsequent games.
Increased chance of The Mysterious Stranger appearing in V.A.T.S., killing a single enemy instantly.
Increased chance of the Mysterious Stranger appearing when using V.A.T.S.
Fallout: The Roleplaying Game
After spending a Luck point, Mysterious Strange appears to assist in combat.