General Information


Home Planet:

Bicksuria (23D)

Other Info
Crimes: Terrorizing Bellwood

Attempted Murder (Ben)

Goal: Bring Ben to her Father

Become Queen of Her Country

Abilities: Shapeshifting
1st appearance: Infernosphere
Arch-enemy: Ben Tennyson
Henchmen/Leader: Unknown

Sii is a shapeshifting alien from the twenty-third dimension. She appeared in the Back in Action: Alien Universe Shorts episode Infernosphere, where she was defeated by Ben and co (Julie, Gwen, Kevin, and Ship). Ben mentioned that the team had fought her before that time, where she was in the sphere form of Cannonbolt. She is apparently bent on bringing Ben back to her father in the twenty-third dimension so that she may take her place as Queen, and properly take the throne from her father, king of Bicksuria, King Maxin.


Sii's natural appearance is as a glowing blue and white cube. The blue represents her shapeshifting organs and biology, while the white represents her source of energy, personality, and memory. The cube cannot be in anyway penetrated. The cubes of Sii's species would be useful as armor, but when her species dies, the blue parts of the cube, which hold together the cube as well, melts like acid. The personality and memory can be used to sustain one of her species in a temporary body.

She has a beautiful, high-pitched voice in most of her forms.

Powers and Abilities

Sii's most notable power is that which allows her to shapeshift into anything, gaining artificial recreations of her forms' powers. Mimicry of her transformations extends only as far as Sii's knowledge of their inner workings; if there are unknown functions to a device, unknown appearances under a mask, or otherwise, she will only work or look as she's imagined herself.

When she uses her powers, her forms are typically scaled to much larger proportions than normal. She normally ends up the size of most Earth skyscrapers (as Ben has noted). This has been because she's not able to concentrate enough to make her forms actual size. She shows in later episodes (such as when confronting Albedo's transformations in No Strings Attached) that she is able to control the size of her transformations.

All of her forms also retain the Bicksurians' blue and white glow. When one of her species grows older, they are able to add the species's layer of skin to hide their natural blue and white glow.

Known Transformations

  • Arburian Pelarota (Cannonbolt's species (only seen in sphere form); after seeing Cannonbolt in battle)
  • Evolved Arburian Pelarota (Ultimate Cannonbolt's species/the evolved form of Cannonbolt's species; after seeing N/A)
  • Snake (with limited intelligence; after seeing Ssserpent on the streets of Bellwood)
  • Aerophibian (Jetray's species; after seeing Jetray almost defeat her)
  • Human (When peacefully roaming Earth incognito; after seeing N/A)
  • Chelsii (Merged transformation with Chelsey Tennyson)
  • Tetramand (Four Arms's species; after seeing Tini of the Galactic Enforcers)
  • Amperii (AmpFibian's species; after seeing N/A)
  • Necrofriggian (Big Chill's species; after seeing N/A)
  • Talpaedan (Armodrillo's species; after seeing N/A)


Sii is very strong, and it took Jetray's blasts to slightly annoy her. Nonetheless, through mimicking other aliens' powers, she enhances them to be as powerful as herself, which allows someone to use the mimicked powers against her by having her (for example), fire a mimicked blast at herself. (An example of this is in Infernosphere when Ben uses Sii's Aerophibian mimicked blasts against her by hitting her tail. Hitting an Aerophibian's tail out of surprise caused her to blast herself). This would shock her into unconsciousness for a short period of time, where she is locked in her normal appearance.

True Form

In her true form, she is totally invulnerable.

Human Form

Sii normally uses her human form, which causes her to incur all human weaknesses, except human illnesses.

Back in Action: Alien Universe

  • In Infernosphere, she is defeated by Ben as Jetray after figuring out that Sii transforms into anything powerful that she sees. She used Snake and Aerophibian forms.
  • In No Strings Attached, she returned using a form merged with Chelsey Tennyson. She then appeared as the henchmen of a Vaxasaurian going by the alias "Overcoat," and later for a Necrofriggian going by "Cotton." She also used a Tetramand form derived from Tini.
  • In Ten Plus Twenty, she appeared in Endgame reporting on her performance on a covert mission, also sitting in on a meeting with Mistress.


Back in Action: Alien Universe



  • Out of all of her transformations, Amperii is the only transformation that mixes Sii's own name into the equation. (Chelsii does not count as it was a merge rather than a transformation.)
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