Monsters that are Boss Monsters. The gene for becoming a Boss Monster is dominant, so most/all children of Boss Monsters are Boss Monsters themselves. Hybrids can become Boss Monsters if the Monster parent is a Boss Monster.
“Wing Ding Gaster was the Royal Scientist before Alphys. He was killed by The Shadowy Figure in...Wing Ding Gaster
“Asriel Dreemurr is the prince of the Underground. They were killed by Humans in 1410. TBAAsriel Dreemurr
“Queen Toriel Dreemurr is the queen of the Underground. She left the role of queen soon after the...Toriel Dreemurr
“The Magma Dragon was the first skeleton. He is also the most powerful monster to have ever...The Magma Dragon
“Grillby Vulcanus is a bartender in the small town of Snowdin. He runs the local bar known as...Grillby Vulcanus
“Gerson Kachhua is an old Monster that lives in the Underground. He was the head of the Royal...Gerson Kachhua
“The Dark Figure is an entity that wasn't widely known about until 2030. He is the main...The Dark Figure