Jeffery Slitheen

Kist Magg Thek Lutiven-Day Slitheen was a member of the family Slitheen. He was the brother of Glune Fex Fize Sharlaveer-Slam Slitheen and the father of Korst Gogg Thek Lutiven-Day Slitheen

Coldfire Construction, under control by the Slitheen, had built their final transducer in the guise of a technology block inside Park Vale Comprehensive School over summer 2008. The transducers were to be used absorb all the energy out of the Sun, destroying the Earth avenging the deaths of the Passameer-Day Branch of their family, while the Slitheen lay safe inside a hidden room in the technology blocks across Earth. They would then use the profits from Earth's remains to buy battlecruisers to destroy Raxacoricofallapatorius' Grand Council.

In September, he killed one Park Vale's teachers, Tim Jeffery, and used his skin as a disguise. With his brother Glune Fex Fize, he began the trial run for the ring of transducers, but it failed. At a science club, Kist tricked the star pupil Luke Smith into coming up with an equation to avoid the overload. The plan started again.

When Maria Jackson killed Glune Fex Fize, he called the rest of the family on Earth to come to Park Vale to capture Luke, Maria, Clyde Langer and Sarah Jane Smith. Luke's equations were wrong, as he didn't know that the Slitheen would draw energy from the Sun, and the capacitor began to overload. The system was reset. Luke started to repair it, but Sarah Jane threw him her sonic lipstick. Luke damaged the machine with the lipstick. While most of the Slitheen and Luke's allies escaped, Kist was electrocuted to death in this incident.

Biography from the TARDIS Data Core article, licensed under CC-BY-SA