Zargath

Zargath was an alien whose Imperial Militia had been at the Powell Estate for only five minutes when the Ninth Doctor used his sonic screwdriver to make it rain. Zargath's people were allergic to water and were quickly defeated.

Some time later, Zargath joined forces with other aliens that had been defeated by the Doctor to try to kill him. He shot Valis, believing him to be the Doctor in disguise. Being a highly flammable gaseous alien, Valis exploded, blowing Zargath to smithereens. (COMIC: Death to the Doctor!)

Behind the scenes
In an interview with Jonathan Morris released in The Widow's Curse the description for Zargath was given as; "half human, half angler fish. He has the jagged teeth of an angler fish and a little light bulb dangling at the front. He should resemble a Star Trek-style monster based around prosthetic make-up". Long before Zargath's debut his species appeared in the 1998 charity anthology Perfect Timing short story The Zargathon Menace, which is not considered valid by this site.