Merpeople are mythical creatures, first mentioned in "Dipper vs. Manliness" by the Manotaurs. A young merman named "Mermando" appears in "The Deep End." Merpeople live underwater, and it can be inferred that they are largely the same as mythological merpeople, being some combination of human and fish.
What may be a skeleton of a merperson can be seen in the Mystery Shack gift shop, although it resembles the famous hoax Fiji Mermaid. In the opening credits, a picture of a merperson like the one in the Mystery Shack can be seen near the end. Actual merpeople appear in the episode "The Deep End," when Mabel befriends a merman by the name of Mermando.
- 204. "Sock Opera" (mentioned)
- 207. "Society of the Blind Eye" (pictured)
- 209. "The Love God" ( )
- 210. "Northwest Mansion Mystery" ( )
- The Manotaurs do not seem to like the merpeople. At one point in "Dipper vs. Manliness," Chutzpar mocked them, calling them "losers."
- Male merpeople's voices change when they are about three years old.
- Merpeople cannot leave the water without suffocating. They can, however, flop around for short distances for a while. They have gills to breathe with, likely at their cheeks (as Mermando couldn't breathe when Mabel grabbed his face), though not visible.
- They can apparently speak and understand the language of dolphins.
- Mermando tells Mabel that his kind "cannot be seen," implying that the merpeople want to keep their existence a secret from humans.
- According to Mermando, merpeople "have like, seventeen hearts."
- They serve as enemies in the mobile game "Mystery Shack Attack."
- Apparently it is legal for merpeople to marry as young as twelve. They can also marry other species.