Clam Guy (1)
This clam-headed monster talks about how he came to Hotland specifically to get a drink. He comments if the protagonist carries around a glass of water and if they dump a few glasses of, or all of the water on the ground.
If the protagonist poured all of the water out of the cooler and dropped it, he talks about how there is now a "private pool" and says worse things have happened.
Business Dudes (2 & 3)
Fox Head (4)
This monster speaks in dialogue ending with a question or a question mark. They complain that their co-workers are not helping them with the reactivated puzzles.
Fuku Fire (5)
This monster was once trapped behind the laser on the west side of the first steam puzzle room. She shows relief over the fact that the laser is disabled since they have been trapped there since the lasers were activated. She shows a resemblance to Grillby, but nothing in-game connects her other than appearances.
Skateboard Girl (6)
Upon being freed, this monster talks about how she believes that school has to be canceled due to the reactivated puzzles. If spoken to twice, she realizes school was on break anyway. She expresses a dislike for school and takes every opportunity to say that it should be canceled.
Heats Flamesman (1, 2, 3)
Heats Flamesman is a small, flame-headed monster encountered in Hotland. Upon first meeting him, he tells the protagonist to remember his name.
He is later encountered on the third floor to the right of the room before MTT Resort. Whether the protagonist tells him that they remember or not, he puts on a flabbergasted expression and remark that he was easily defeated. Speaking to him again after the protagonist tells him that they remembered his name earns the response "I'll always remember that you remembered!" Likewise, if the protagonist forgot he responds "I'll never forget that you forgot!"
Hot Dog Harpy (4)
This monster is seen near Sans's illegal hot dog stand. She comments on the fact that he has not cleaned the snow off of the roof of his hotdog stand, and deems it a result of his laziness.
Hot Dog Vulkin (5)
This Vulkin can be seen near Sans's illegal hot dog stand. They express joy over having obtained a hotdog.
Scared Donut Guy (1)
This monster was convinced by Muffet to buy one of her spider pastries and ended up spending all of his money. He resolves to not buy anything from spiders while on the surface in the True Pacifist Route ending. One of W. D. Gaster's followers resembles him.
Diamond Boys (2 & 3)
These monsters only appear after the protagonist solves the northern puzzle on the third floor of Hotland. They are fans of Mettaton who talk about their favorite moments of his show. What they say are actually hints at what to do to gain ratings in Mettaton's boss fight. In the True Pacifist epilogue, the purple one expresses interest in getting a "sick skateboard", while the green one is excited at the prospect of watching other kinds of television before presuming that none of them are as good as Mettaton's show. One of them can be seen watching Mettaton's stage show in the True Pacifist Ending Credits. They both feel sad if Mettaton is killed.
Dress Lion (4 & 5)
This lion-like monster is a big fan of Mettaton, admiring his talent. In a True Pacifist ending, Mettaton gives them his dress. They can be seen at the end of the True Pacifist Ending Credits watching Mettaton's stage show. If Mettaton is killed, they feel discouraged about something and will not want to talk to the protagonist.