Bandit

A bandit on the party's side is hired muscle, a deserter, or a prisoner conscripted under duress. The framing matters because a bandit who chose to be there acts very differently from one who's there because the alternative is the gallows. Pick which kind of relationship the party has and play it consistently.

In combat the bandit is a CR 1/8 mook with 11 HP and a +3 to hit, which means they exist to absorb one attack and contribute one swing per round. Don't try to make them tactically clever. They take the shot the party tells them to take, hit on roughly half the time, and go down to almost any saving-throw spell aimed near them. Give them a name and a bad joke they tell twice per session, and the table will care when they finally drop.

Bandits as allies are loot generators. They know what fences pay, where the back door of the warehouse is, who in the city watch takes bribes. Use them to give the party plot information the party didn't know to ask for. They also know other bandits, which means a single ally bandit can introduce the party to a whole criminal network or get them invited to the kind of meeting they'd otherwise need three skill challenges to attend.

The bandit will betray the party for the right price, or for the wrong threat. Decide in advance what that price or threat looks like, and let the players see the moment coming. A betrayal the players half-expected is a great scene. A betrayal that comes from nowhere is a cheap one.

Bandits don't survive solo encounters and shouldn't try. They're an action-economy problem: 4 to 6 bandits make a level-2 party sweat, one bandit is a speed bump.

Run them in groups with a clear plan. Position 2 to 3 with light crossbows on cover or rooftops, 2 to 4 with scimitars in melee. Range matters because Light Crossbow is +3 to hit at 80/320 ft., so spread the archers out and force the party to choose between charging them or screening the casters. The melee bandits should Disengage rather than die. If a scimitar bandit drops below 5 HP, they back off and fall in with the archers, ideally collecting a few points of cover on the way.

Bandits negotiate. They demand coin, then rings, then the boots, then the cart. They run the moment the encounter goes obviously sideways: when the cleric drops Bless, when the ranger one-shots one of them, when a fireball lands. They are cowards and that's their charm. A bandit fight with no roleplay is a wasted encounter. A bandit fight where the leader stands on a stump and tries to extort the party is memorable.

Use them as a tutorial encounter for the things the party will face later. Have one bandit feign death and then run, which teaches "not everyone is dead just because they fell." Have one surrender and become a lead, which teaches "you can take prisoners." Have the leader carry a key or a letter, which teaches "loot tells stories." A bandit fight is the cheapest way to teach genre conventions.

Name the bandit leader. "The bandits attack" and "Marek the Crooked-Eyed steps from behind a tree" are the same encounter with very different stickiness.