Even though we've already won the fight for Earth, we're still trying to keep it safe! There are battle-damaged Gems that are still around, and they're not like us. Something's really wrong with them. They're like horrible monsters. We have to poof their bodies away, and then keep their Gems inside of bubbles, so they can't form again and hurt anybody. Maybe someday I'll be able to heal what's wrong with them, but I'm not sure how. Mom couldn't fix them either. For now, we're keeping them safe inside the Temple.
~ Steven

The Gem Monsters, also known as Corrupted Gems, are recurring antagonists of the Cartoon Network TV series Steven Universe.

Throughout the series, the Crystal Gems hunt, collect and bubble their gemstones to their temple to keep Earth safe from them. They take on monstrous forms and have special abilities. Some of them like the Centipeetle Mother and Big Bird are able to make smaller copies of themselves. In Ocean Gem, it's revealed that the Gem Monsters are corrupted gems who were former Crystal Gems and possibly Homeworld Gems who became unable to sustain sentience and humanoid forms when the Diamonds sent out a Corrupting Light.

As a last ditch effort in the war for Earth, the Great Diamond Authority sent out a Corrupting Light which corrupted Gems from both Homeworld and the Rebellion that had been left on Earth, most likely a means of ensuring the rebellion couldn't directly threaten Homeworld.

Second-hand corruption can occur to a non-corrupted Gem through fusion with a corrupted one, as Jasper started corrupting after fusing with the Snow Monster and forming a semi-corrupted fusion.

Corruption id depicted as a tear in the mind of a Gem, rather than physical damage on their gemstone and as such is harder to heal than a cracked Gem: in fact there is currently no known way for reversing the effects of corruption.

Steven's healing spit only partially and temporarily healed the Centipeetle Mother, and she reverted to her corrupted form shortly after. But even so it is acknowledged as a major step in trying to heal the Corrupted Gems even though Steven's attempt went only so far, saying that it was the best that they have seen it work. She indicated that Rose Quartz was unable to heal the Corrupted Gems to the same extent her son, Steven, had done.

Known Corrupted Gems


  • Mollusks
  • Glass Ghost
  • Obelisk
  • Rainbow Cloud Monster
  • Old Book Gem
  • Snowbeast
  • Slug Monster
  • Plant Monster
  • Manta Ray
  • Clock Tower
  • Unknown Giant Bird
  • The Perils of Pweepwee
  • Vine Monsters



           Steven Universe Villains

Great Diamond Authority | White Diamond | Yellow Diamond | Blue Diamond | Pink Diamond | Homeworld Gems | Peridot | Lapis Lazuli | Jasper | Yellow Diamond's Pearl | Blue Diamond's Pearl | Eyeball Ruby | Navy Ruby | Holly Blue Agate | Aquamarine | Topaz | Emerald | Robonoids | Fusion Gems | Sugilite | Malachite | Unknown Quartz Fusion | Gem Monsters | Centipeetle Mother | Gem Cave Creature | Big Bird | Ice Monster | Invisible Gem Monster | Lighthouse Gem Monster | Slinker | Great North Gem Monsters | Cluster | Bismuth | Marty | Frybo

Video Games