Can You Play Mafia or Werewolf With 5 or 6 Players?
There are social deduction games that can be played with five or six players, but I would not necessarily call them Werewolf or Mafia.
The progressive rounds of player elimination help to build tension in the later stages of the game. Having at least two evil players who know each other is also part of the mystery for the village to solve: who is working together as a team? With fewer people, it is difficult to get both mechanics into the game.
What an extra life changes
To tweak Werewolf for smaller numbers, my group started a variant we called doubles. Players were dealt two cards, one from each of two piles. Two Villager cards gave a villager two lives, lost either through execution or a wolf attack. This meant more phases could be played, with useful information coming from an execution that failed to kill anyone.
A night attack could take that spare life without telling the player. If the werewolves had targeted them the night before, they would not know until they swung in the gallows. Surviving an execution was public, so it gave the group something to work with as well as keeping another player in the game. This was the inspiration for the Enduring aura on werewolv.es.
Mafia or Werewolf with 5 players: the parity problem
Two wolves against two villagers was still a wolfpack win, however many lives those villagers had left. A wrong execution that killed a villager could still end a five-player game immediately. The extra life helped when it prevented that death; it did not make every execution safe.
We never played doubles with five players. The proposed five-player adaptation also risks ending before the first day: if a wolf attack kills a village player with only one life, two wolves and two villagers remain. Starting without a first-night kill avoids that particular ending, but the simulations did not establish a balanced five-player setup.
Mafia or Werewolf with 6 players
Six players leave more room. One opening village death leaves two wolves against three villagers, rather than immediate parity. In the simulated six-player doubles games, normal opening attacks still favoured wolves.
The six-player Mafia and Werewolf setup guide gives the card lists, exact rules and simulation results. It also describes an untested suggestion to replace one wolf with a Bloodmoon Cult supporter who knows the wolf, without the wolf knowing them.
What about 7 or 8 players?
The same guide includes card lists and simulation results for Werewolf with 7 players and Werewolf with 8 players. Those lists extend the six-player deal. Seven came closest to even under both tested bot models, while eight favoured village. Those are simulated outcomes, not evidence of human balance: more players did not simply mean a more balanced game.
Other games for five or six players
Resistance, Avalon, Secret Hitler and Salem 1692 work fine at five or six players. You do not have to keep changing Werewolf if what you want is a social deduction game for the people you have.
For comparisons across more formats, see other social deduction games. For the wider design problem, read what small Werewolf and Mafia games lose. If you want to develop a setup, the balance guide explains how information and claim space affect it.