Panther

A panther as ally is the classic Find Familiar for warlocks, a ranger beast companion, or a druid's wild shape in jungle campaigns. With Stealth +7, 50 feet walk, and 40 feet climb, the panther is a perfect scout and shadow.

Out of combat, give the panther work that uses the stat block. She climbs to scout the temple roof. She pads ahead through the jungle and signals back when there is movement. She holds Stealth in a copse while the rest of the party makes noise on the road. Rule that her tracking gives Advantage on Survival checks to follow scents in wet terrain.

In combat she is fragile. AC 13 and 13 HP means a single goblin critical can drop her. Use Rend for one assist, not a full combat shift. The classic move is the pre-fight pounce: the panther sneaks ahead, drops on the lookout, silences the alarm before the rest of the party rounds the corner. Use Nimble Escape to disengage and stay out of melee after.

If she dies, take a beat at the table. The player picked a panther for a reason.

A panther is a CR 1/4 stalker, 13 HP, AC 13. Stealth +7 is the highest on this section of the bestiary. It has a single Rend attack at +5 doing 1d6+3 slashing and Nimble Escape to take Disengage or Hide as a bonus action each turn. The encounter is the ambush.

Use geography. Walk 50 feet and climb 40 feet mean the panther starts on a tree branch or rafter, watching. Roll Stealth at +7 against passive Perceptions; if the panther wins, the first PC within 50 feet of its position is on the ground with a cat on top before they get to act. At low levels that single round can end someone.

Run the panther as an executioner in a larger scene, not as the whole encounter. A scout cult uses one as their tracker. A drow patrol has trained one to climb walls in the Underdark and pounce on the torchbearer. The panther costs 50 XP but changes the texture of the bigger encounter completely.

The panther flees as soon as it is hurt. With 13 HP it cannot trade and it knows it. Once a PC connects, the cat breaks off at 50 feet of speed, climbs the nearest vertical surface at 40 feet, and is gone before round two. The party will not catch it. That escape is the encounter, because the same panther can come back the next night.

Describe the smell of cat before you describe the cat. Damp fur, blood, wet leaves.