- "The Nightmare Knight created seven monsters and appointed them to rule over the conquered kingdoms of Dreamside. They became known as the Disaster Masters, and each one was more powerful than the last."
- — Princess Nautilus 
The Disaster Masters are seven monsters which rule the kingdoms of Dreamside in the event that the Nightmare Knight is summoned. Each one has a corresponding Disaster Stone that is given to the Legendary Hero when the Disaster Master is defeated.
Main Article: Splashmaster
Splashmaster is the slow, squid-like ruler of the Ripple Kingdom. What he misses in smarts, he makes up for in power and a sore loser attitude. When defeated, he released the Splash Stone, which gave Cucumber the ability to use powerful water spells.
Main Article: Noisemaster
Main Article: Mutemaster
Mutemaster is the second Disaster Master in charge of the Melody Kingdom along with Noisemaster. Unlike Noisemaster, he is large and quiet, with the ability to cover things with complete silence.
Main Article: Rosemaster
Rosemaster is the fourth Disaster Master introduced in Cucumber Quest, and she resides in the Flower Kingdom. She has the ability to alter the memories of people with plant-based names, and in her super form, even control their minds.
Main Article: Quakemaster
Quakemaster is the Disaster Master to first attack the Crystal Kingdom. He seems to have lava-based abilities, as well as the power to turn people to stone.
The Forsaken Master Edit
Main Article: Forsaken Master
Unlike the other seven Disaster Masters, the Forsaken Master was sealed away by the Nightmare Knight himself and, while it is unknown if it has a Disaster Stone, is not required to revive the Nightmare Knight. Sealed within the Glass Mountain in the Crystal Kingdom, the Stone Seal keeps the Forsaken Master and its terrifying powers at bay.
However, the Forsaken Master is no threat whatsoever to Cucumber and Co.
Main Article: Glitchmaster
In Interlude 2, the Heroes were confronted by a very strange apparition, taking the form of the Nightmare Knight but with a pixellated appearance, pink/red eyes, and missing the Nightmare Knight's star on their chest. Immediately prior to this, Cosmo had been teleported away, although they had begun saying a name, "Glitc--". It is commonly believed that this was Glitchmaster, the Disaster Master of the Space Kingdom, who was officially named by Rosemaster on Page 579.
Main Article: Mistmaster
Mistmaster appears in Chapter 5, where the Nightmare Knight visits them. They are made up mostly of fog and mist, and seem to be in a miserable state. They are also claimed to be the source of all rain by the Nightmare Knight.