Husk

The Husks were the former bodies of Josiah Samuel Smith, an alien survey sent to Earth by Light. They did not have much use apart from uses as henchmen to Josiah Samuel Smith.

Appearance
Josiah did not appear humanoid in his original form and therefore began to evolve into the dominant species at the time: The Victorian Gentleman. This process appeared to take some time. There were two husks in the lower observatory of Gabriel Chase; one of these looked like a reptile, the other like an insect. Both wore clothing very similar to Josiah's.

The third husk was created in the upper observatory after Josiah abandoned his interim state, in the manner of an insect, completing his evolution. This husk was exactly the same as Josiah's final appearance, except that it had flaky skin. (DW Ghost Light)

Characteristics
The Husks were free to move to a degree, the ones in the lower gallery endeavored to capture Ace but Nimrod fended them of with a lantern. All the husks, and Josiah's interim state just before complete evolution, were afraid of light, it is strongly implied this was because Josiah associated light with Light, his master. (DW: Ghost Light)

Behind the Scenes
According to the writer, Marc Platt, Husks were placed in the story because the first two episodes lacked monsters.

There was originally meant to be a third husk in the spaceship looking like a fish.