Ilmatar
Ilmatar was a singer with the ability to cause sympathetic vibrations with his voice, burning people to death. He did this to a number of his audiences for the amusement and hunger of the Grosche. He looked like a genderless dark angel.
On Earth, Ilmatar was the lead singer of Zeal until, in the 1980s, he used his voice to kill his bandmates and his audience of 350 people. He became an opera singer and planned on roasting another audience for the Grosche in the late 2000s, killing Sigmund Wallfisch but being figured out by Ianto Jones and Toshiko Sato. They figured that they would catch him in the future. (AUDIO: Dinner and a Show)