Whifferdill

From Tardis Wiki, the free Doctor Who reference

Whifferdill were a shape-changing species from the planet Xenon. (COMIC: Voyager) Their real form was a Humanoid, pale yellow in colour with a round, featureless head. (COMIC: The Shape Shifter) Their shape-changing abilities could be stopped if they were infected with mono-morphia. (COMIC: Genesis!) They were related to Kymbra Chimeras, another shape-shifting species. (COMIC: Changes) Frobisher was a Whifferdill, but he developed mono-morphia for some time. (COMIC: Genesis!) They could turn into anything. There are only approximentally 15 left. They are an endangered species.