Miranda Cleaves was a 22nd century Earth Acid miner.
Like most workers in hazardous conditions, Miranda and her co-workers used Gangers as surrogates. When a bolt of solar energy struck the facility, the Gangers were all given independence. Despite the words of the Doctor, who urged her to accept that the Gangers had become truly alive, she saw them as a threat, and killed one of them, before declaring war on the others. (DW: The Rebel Flesh)
The Doctor diagnosed her with an inoperable (on Earth) blood clot in her brain, her Ganger is also seen to have it. Whilst on the TARDIS, the Doctor cures her by getting her to take a small red vial that tastes a bit like "burnt onions."
