Reputation is the opinion of a specific group of people towards the player character based on their actions.
Fallout 2
Reputation in Fallout 2 is a way to measure general feeling for your character in each of the towns visited. Reputation can be modified by doing good or bad deeds.
Fallout Tactics
Reputation in Fallout Tactics is the reflection of what people think of the player character, based on their actions. Characters start with the reputation of a Warrior and move up or down from there.
Fallout: New Vegas
In Fallout: New Vegas, reputation among various factions will be tracked. There are many different factions in the wasteland, and actions will influence one's reputation with each one. As one performs actions that benefit a group, they will gain Fame. If performing actions that harm a group, one will gain Infamy. Reputation with any given group is a measure of the combined total of Fame and Infamy earned. The benefits and drawbacks of any given reputation depend on the group itself. One may receive discounts with merchants, provoke attacks from hired thugs, or influence dialogue options.
Fallout 76
Reputation is a gameplay mechanic introduced in Fallout 76, introduced in the Wastelanders update. It is a system that linearly logs both good and bad player character's actions with the two main factions of living humans, the Settlers and the Raiders. Positive dialogue choices and completing quests and dailies for the faction are ways to gain reputation.
There are 7 reputation ranks: Hostile, Cautious, Neutral, Cooperative, Friendly, Neighborly, and Ally. Reputation also includes special faction items, available for purchase after certain ranks are achieved.
Fallout: The Roleplaying Game
Reputation is an optional rule presented in the GM Toolkit. Reputation is meant to track the standing of the group against the variety of factions that could be present in any game run. Depending on the group standing, factions can be relied on for help and other forms of assistance should a faction be called upon. There are various factors that can increase or decrease the reputation for a faction depending on factors such as completing objectives asked in favor of a faction and killing members of that faction to fulfilling promises and or going against their beliefs.