Caliban is tall and lanky, standing at least two heads taller than Dr. Weller. He has a skeletal humanoid design with a gray, white and red color scheme, alongside cyan highlights. He has a used and cobbled together look as the paint on his chest has been scratched, has a scratch on his head and is missing the housing on his right leg. His arms are also mismatched and seem to be from two completely different robots. His head is rather rectangular and vaguely resembles that of a human, and lacks distinct facial features, barring the exception of two pairs of cyan eyes.
In the game Siege, Caliban appears as a medieval knight.
Caliban is loaded with a sliver of Dr. Weller's own neural pattern, and as such, is in possession of his memories and ideas, and is thus aware of all of the intricacies, theories and future plans related to the gen:LOCK program. He also has several personality traits carried over from Weller, most noticeably his penchant for bad jokes and puns, which come across as even worse than Weller's due to his stilted, robotic delivery.
Caliban is capable of using gen:LOCK equipment to link a pilot with his or her Holon. Despite being resistant to bullets, Caliban does not seem to have any offensive capabilities beyond hand-to-hand combat.
- Caliban may allude to Caliban, a character in William Shakespeare's The Tempest, who is a pseudo-human servant to the main character Prospero. His cobbled together appearance and the fact he contains a sliver of Doctor Weller's mind is likely a reference to his monstrous namesake. 
- The name may also simultaneously be a subtle callout to the description by the late American writer Russell Hoban of Caliban's Shakespearean namesake as 'a necessary idea'. In other words, Caliban was a necessary step (upload testbed) for the gen:Lock project to proceed.