|ANIME DEBUT||Episode 6|
|MANGA DEBUT||Chapter 8|
Cancer Cell (がん細胞 Gansaibō?) is a recurring antagonist in Cells at Work!
He was born mutated because the normal cell who grew him made a copying error in his DNA. His mutation causes him to appear different from normal cells and to replicate uncontrollably, causing potentially deadly cancer.
Cancer Cell's hair is dark when in disguise and light in his true form, and his right eye has a black sclera. There are growths on his skin (most notably his cheeks) that resemble bulging veins. His body is constantly changing shape, size, and number of limbs. He wears a normal cell outfit.
He is intelligent and manipulative, easily gaining the trust of the other cells while in disguise and almost succeeding in his plan to take over the body. He is ruthless in his pursuit for his goal, willing to kill off the entire host body so that he can reproduce and spread.
Due to being a defect, Cancer Cell was persecuted by other immune cells who wanted to have him killed. This caused him to harbor a deep-seated hatred toward all of the other functioning cells in the body, as he believes its not fair for him to be eliminated when he had no control over the circumstances of his birth. Despite this, he is ultimately jealous of the other the cells, as they were given a purpose in life while he was deemed a mistake that should simply be killed off. He has a fondness for U-1146 for protecting him from another cancer cell when he was disguised as a normal cell, and for showing a "kind-hearted" demeanor despite his purpose of killing threats to the body.
Despite the serious threat potential he possesses, he is still somewhat of a tragic figure, as he never asked to become what he was and was shaped by forces and events beyond his control.
The full abilities of Cancer Cell is unknown; his power seems to grow stronger on bacteria toxins.
- Combat Proficiency: Cancer Cell is a formidable opponent to immune cells. He fights hand-to-hand without a weapon.
- Shapeshifting Mutation: He can dramatically change size and shape at will to help him fight and overpower immune cells.
- Metastasis: When he wants to spread cancer throughout the body, he grows feathered wings for fast travel.
- Recurrence: Cancer Cell was able to "resurrect" with his memories intact after his genes were leaked.
- Regeneration: He is able to regenerate and heal any injured parts of his body if the received attacks are not fatal.
- ↑ Cells at Work! Manga, Chapter 9 and Chapter 25