Phantos are large, seemingly living or possessed masks that can often be found guarding various treasures, most often keys. Its name appears to be a shortened form of the word "phantom", another word for ghost or spectre. Phantos appear as semi-common enemies in Super Mario Bros. 2, often in caves or in vases. Phantos simply remain immobile unless the key they are guarding moves. Once this happens, a Phanto will ceaselessly chase whoever stole its key. Phantos cannot be avoided and can only be escaped by using the key it was guarding to unlock a door. If the player simply drops the key while a Phanto is chasing them, the creature will fly away and leave them alone, at least until the key is picked up again. Phanto can even follow the player into Subspace. Phantos can only be defeated with a combination of a Stop Watch and a Star; having only a Star will not affect it. After destroying a Phanto, however, a new one will replace it if the player enters another room while still carrying the key.
Phanto is depicted in two ways; originally, Phanto sported a very solemn demeanor in Yume Kōjō: Doki Doki Panic, while in Super Mario Bros. 2, it is given an evil grin. The former representation is often used in character art.
Two Phantos made appearances on The Super Mario Bros. Super Show!. The first one appeared in the episode "The Ten Koopmandments". This Phanto lived in a pyramid that Koop Tut had trapped Mario, Luigi, Princess Toadstool and Toad inside. Upon discovering the four heroes, it proceeded to chase them until they managed to escape from the pyramid. Another Phanto made a brief cameo appearance in the episode "Escape from Koopatraz", as a member of Judge Koopa's jury.
 Names in other Languages
||From the word spettro ("spectre")
- In Chapter 6-3 of Super Paper Mario, the Sammer Guy guardian of the 63rd gate is named "Phanto Grin".
- A Zebra Mask (which resembles a Phanto) is one of many collectible treasures featured in "The Great Cave Offensive" mode of the games Kirby Super Star and Kirby Super Star Ultra. The Zebra Mask is located in the Sub-Tree Area of the Great Cave, and is worth 278,000 Gold. In the English version of Kirby Super Star Ultra, it is renamed the Phanto Mask.
- In Kirby's Dream Land, an enemy known as "Two-Face" appears. This foe bears a striking resemblance to Phanto, and even attacks in the exact same way, though Kirby is able to inhale it or destroy it with a projectile.
- Dimentio's mask has a similar appearance to a Phanto.
- There is an enemy in the Kirby series called a Kabu that is similar to the Phanto, in the sense that they are both floating masks that chase Kirby/Mario.
- The Super Mario Bros. 2 sprite of Phanto can be spotted in the Mario Kart 7 course Shy Guy Bazaar, stitched into a rug on the ground along with the sprites of other characters.