Blindheim

Let’s be honest: blindheims are mostly set dressing.  At CR2, they’re only going to be a threat to the most novice of parties.  But for atmosphere, they’re phenomenal.  With their glowing eyes and eerie silence, they introduce PCs to a new underground world.

A novice party of adventurers, fresh back from their first sortie against goblin raiders, plummet through a sinkhole down a deep dark shaft.  Giant pillowy bracket fungi and mushrooms arrest their fall on the way down, sparing them from damage, but now they must find their way back to the surface.  And even as they scramble to orient themselves, four pairs of glowing white eyes light up the dark, focusing on them.

Below the earth, wherever there is water, there are predators.  To combat this, an outpost of svirfneblin has befriended the local blindheims with food.  Now the frog-like creatures stand watch over the cavern where the svirfneblin fetch water and bathe, alerting them to dangers—including surface adventurers.

A drow wizard specializes in light spells to dazzle his sun-hating rivals.  He keeps three blindheims on a chain and takes them for walks through the dark city.  Their flashing white eyes are meant as a deliberate insult.

—Pathfinder Bestiary 2 46

It is totally fine to shut off the lights and shine flashlights while role-playing a blindheim.  Wearing a frog mask might be a little much, though.