C'rizz (pronounced as "Cerys") is a fictional character played by Conrad Westmaas in a series of audio plays produced by Big Finish Productions based on the long-running British science fiction television series Doctor Who. An Eutermesan from the planet Bortresoye, which exists in a parallel universe, he is a companion of the Eighth Doctor. The canonicity of the audio dramas with respect to the television series, like other Doctor Who spin-offs, is open to interpretation.
When C'rizz meets the Doctor and Charley, he is suffering grief from the loss of his mate, L'da, whom he had left behind when he escaped the Kromon biodome. Together with the Doctor and Charley, he returns to rescue L'da and free his people from the Kromon. He succeeds in the latter, but is forced to kill L'da, who had been transformed into a Kromon queen. Still coming to terms with what he had to do, he asks to join the Doctor and Charley as they proceeded to the next zone in search of the TARDIS and the answer to the mysteries of the universe they were in.
Eventually, it is revealed that C'rizz was an adept of the Church of the Foundation, which believed that all things must die, and had murdered in its name before he met L'da and left the Church. It is also revealed that the Eutermesans are more than physical chameleons, but emotional and mental ones as well, shaping their personalities to those around them but also making them easily manipulated.
When the Doctor and Charley finally manage to return to their own universe, C'rizz continues to travel with them, as he trusts the Doctor to keep him stable and himself. They emerge on an Earth conquered by the Daleks, who try unsuccessfully to brainwash C'rizz into becoming their new Emperor. The Dalek attempt adds to C'rizz's deteriorating mental state: in Terror Firma he continues to hear, in his mind, the voices of the people he killed.
In Absolution, C'rizz is granted massive psychic powers on a planet that resembles Hell with citizens who have been turned to demons save one domed city, eventually transforming into a physical form that Charley likens to Lucifer. The Doctor theorizes that the Eutermesans genetically engineered C'rizz to house their souls in some mad bid for immortality. C'rizz eventually gives up his new form and powers by restoring the planet and its citizens back to their original forms. This action exhausts C'rizz, who then thanks the Doctor for healing his emotional wounds (save for L'da's death) and calls Charley his sister before dying, his body turning to ashes.
The impact of C'rizz's death will be felt in The Girl Who Never Was.