One unassuming Dungeons & Dragons monster has the power to create gods...literally. The kuo-toa are a classic Dungeons & Dragons monster that made their first appearance in the classic Shrine of the Kuo-Toa adventure back in 1981. Over time, the kuo-toa have slowly morphed into something pulled straight out of an H.P. Lovecraft story, but early adventures depicted them as a type of fish-person able to live either on land on in the water.
When players first encountered the kuo-toa in Shrine of the Kuo-Toa, they learned that the fish-people were devout worshipers of a strange god called Blibdoolpoolp - a god with the body of a human woman, but with the head and arms of a lobster. Blibdoolpoolp was presented as a real god from the onset, but later Dungeons & Dragons publications revealed that Blibdoolpoolp was literally willed into existence by the kuo-toa. Due to some ancient psychic power, the kuo-toa can collectively will a god into being simply by believing it's real. Blibdoolpoolp was originally a statue that some kuo-toa cleric grafted lobster parts to, and then convinced other kuo-toa that it was a real god. Blibdoolpoolp eventually was created out of sheer kuo-toa belief, complete with her own magic abilities, sentience, and even her own realm within the Elemental Plane of Water.
Because the kuo-toa are fervent believers of....well, anything that presents itself as a god, other creatures often take advantage of them. Aboleths and kraken are often worshipped by kuo-toa and use their unwitting flock as minions for their own schemes.
Individually, the kuo-toa aren't much of a threat, but a kuo-toa collective can pose an interesting threat to a D&D party. Maybe the kuo-toa have taken to worshipping another non-sensical god, resulting in the new deity threatening a nearby village or city. Or maybe an encounter with the kuo-toa resulted in them worshipping one of the players, resulting in a mad god who looks like a ghastly reflection of a member of your party. The kuo-toa's unique ability to create gods can make for a memorable D&D session, provided that a party doesn't get sacrificed as an offering to Blibdoolpoolp first.