Boar

A boar on the party's side is a familiar, a druid's wild shape, or a hunting pig that someone bought at a market and trained badly. The most common framing is a ranger or druid character who has bonded with one as a companion. The boar is loyal in the way pigs are loyal, which is to say, to whoever has the food and the scratching stick.

Use the boar as a wedge. Walk speed 40 ft. lets it close on enemies a turn before the rest of the party arrives, and at AC 11 with 13 HP it absorbs one or two hits before it goes down, which is one or two hits the cleric did not take. Do not ask it to do anything clever. It charges, it bites, it stands on whatever fell over. If the handler points at a target and shouts, the boar runs at the target. If nobody points, the boar runs at the loudest noise.

The texture is in the social scenes. A boar in a tavern is a problem. A boar in a temple is a worse problem. Lean on the comedy and on the genuine attachment the handler has to it. When the boar finally dies, and at CR 1/4 in a real fight it will, treat it like a real loss. The handler buries it. Someone says something. The party moves on heavier than they were.

A boar is a wilderness encounter that punishes parties who treat the woods like a hallway. With 13 HP and AC 11, one boar dies fast against a level 1 party, but it is a beast with Bloodied Fury and a charged Gore attack that makes it dangerous. Boars are territorial, they do not care about wounds, and they charge anything between them and the piglets. Run them in pairs or sounders of three to five and they become a real fight.

Open with a charge from cover. The boar's walk speed is 40 ft., which is faster than a PC in heavy armor, and Passive Perception 9 means it does not notice the party until they are close, so the surprise can cut both ways. Whoever is on the path or between the herd and the brush gets rushed first. The Gore attack at +3 to hit deals 4 damage (1d6+1), or 7 (1d6+1 plus 1d6) if the boar charged at least 20 feet and knocks the target Prone. While bloodied (below 6 HP), the boar has advantage on attack rolls and becomes more dangerous, not less. The animal is not strategic. It picks the nearest moving thing and runs at it. If a PC drops, the boar will keep mauling them on the ground rather than turn to a fresh target.

Boars do not retreat from a fight they entered, but they do disengage if the party clearly threatens the young. Have a sow break off if the party moves toward the piglets, and let the others follow. This gives the table a clean exit that is not just a slog to the last hit point. If the party kills the lot, leave a survivor in the underbrush. A wounded boar tracking the party for half a session is more memorable than the encounter that produced it.

Treat boars as a setting tile, not a fight. They tell the players the wilderness has its own rules.