A Redirector is a role that causes all actions taken on a particular Night by a specific player to target a specific second player instead of whatever their original target was.
The name Redirector is sometimes used to describe a Deflector instead, but this practice is discouraged nowadays.
A Captain can also change the target of other players' abilities, but only those of specific other players, and those players normally have an option to refuse to use their action in response to discovering their target.
Use and Power
In the majority of cases, players are not informed that their Night actions were redirected. As with Deflectors and Bus Drivers, there is no consensus about whether an investigative role should be made aware of this redirection via their report or not; see Dealing with Scum Bus Drives.
Mafia Redirectors serve a similar function to Roleblockers in practice; a player's action can typically be neutralized via redirecting it onto a useless target, such as directing a Cop onto a confirmed player, or a Doctor onto a player who is not the target of a nightkill, although it is a bad idea to allow one into the same setup as a Vigilante or Serial Killer. In Town's hands, it is a little more powerful, due to the risk that it can be used to wrest control of the Mafia's nightkill into Town's hands. For similar reasons, it is normally a bad idea to allow a player to force another player to self-target, especially if that player is Town-aligned; this would give them the effect of a Vigilante kill that only worked on anti-Town players (who typically have kills).
In setups where multiple scumteams exist, but (for balance reasons) only one of them has a nightkill, giving the other team a factional Redirector ability is a common way to give them influence over the game at Night – in particular, this lets them take control of the nightkill if they can guess who is performing it.