Unique monsters

[Vipersfang]

I'm running a game for 4 6 level players. I'm looking for monsters with unique abilities or unique monsters...

[breithauptclan]

Easiest way is to build you own.

[Perpdepog]

You can also do a search on Archives of Nethys for the Unique trait on monsters and see what comes up. They will have ties to Golarion's lore, but you can repurpose the backstory if you want.

I would also recommend considering reskinning. Swap damage types, size categories, creature traits, and give it a new description and you can get a lot of mileage out of a handful of monsters.

Aside from that, what do you mean by "unique?" What makes a monster or ability unique versus another?

[Ravingdork]

Another alternative is to use an existing monster, but totally reskin it, changing nothing but maybe traits and size.

For example, an owlbear could be reskinned as a doped up barbarian berserker with knives, a sentry robot with scythe arms and a blaring speaker for a head, an alien ooze made of loudly grinding razor nanotechnology, or a wheeled dwarven construct with lots of deadly spikes and a loud steam vent.

[HumbleGamer]

Put them against an alchemical golem and wait for them to critical hit a strike.

[Sauce987654321]

Not to sound rude or anything, but your question doesn't really say very much. What is unique to you? Do you mean creatures the game considers uncommon? If not, any creature can be as common or unique as you want them to be in your game.

[The-Magic-Sword]

I think they're just looking for cool ideas in that level range.

Desert Giants are pretty cool, they can run around the battlefield while striking, making your party waste actions catching up, especially since its faster than them.

Tupilaq are pretty fun, if you don't mind looking for some fun spells, your players won't be expecting these little things to start throwing random third level spells around.

More on the boss 'extremely deadly boss at level 6' side of things Witchfire is pretty wild, especially if you pair it into a plot about Hags, because I also notice there's a bunch of Hags in this level range. Maybe have the players encounter a variety of Hags all gathering in a region, using their coven mechanics and the different types would make it a pretty exciting adventure with a lot going on. especially (but not exclusively if your players are super well optimized) if it goes on long enough to get them to level some, you could very reasonably use the Witchfire as a boss.