Multiforms are a species of sapient shapeshifters whose natural form resembles an elongated worm or eel, with metallic-blue skin, needle shaped teeth and yellow eyes.
They have a natural lifespan of thousands of years, and are able to escape danger by shifting their bodies into liquid or dust. The ability to perfectly mimic other lifeforms (to the point of tricking the sensors used by the Atraxi) is far more complex, and requires the establishment of a telepathic link with a host, which takes months to stabilize. After the link is formed, the Multiform is able to put the host in comatose state and assume a form created by the host's imagination. The illusory form often appears like multiple beings, although these are always in physical contact with each other and retain a single mind.
- Multiforms are mentioned among the visitors to Platform One five billion years in the future in "The End of the World". This predates their actual debut in "The Eleventh Hour" by five years. Presumably, they were assuming a different form on that occasion.
- Doctor Who new series Season 5 – "The Eleventh Hour" (2010)