Ballon

Ballon was a Lore, who travelled to Earth as a refugee following the destruction of his home planet.

Since Operation Double, Zygons were protected on Earth, and so Ballon posed as one in order to avoid detection by UNIT. He was instead captured by the Governors.

The Governors imprisoned Ballon until he came of use. He joined Dorothea Ames and Andrea Quill on a mission to remove the arn from Quill's brain, and became the surgeon responsible for doing so. (TV: The Metaphysical Engine, or What Quill Did)