Dr. Cletus Poffenberger is an ex-scientist, more specifically a retired biochemist. He worked in a now-abandoned lab owned by the Proudfoot Corporation, somewhere near Perfection and helped create a chemical called Mixmaster, which can mix any non-human DNA to create new forms of life. When any such creature threatens Perfection Valley he is often called in. He was first introduced when his personal pet Project 4-12 escaped and terrorized the inhabitants of Perfection Valley who were surprisingly used to monster attacks. He has apparently been watching the valley for over 30 years and seen a lot of things. He can be very intimidating as Twithcell found out. He enjoys Nancy's company and has moved to Perfection after the death of 4-12. He often lends his scientific advice to situations caused by Mixmaster and often collaborates with other scientists if his knowledge is too limited. He was portrayed by veteran sci-fi actor Christopher Lloyd.
- Tremors: The Series
- Tremors: The Lost Episodes
- The Thing in the Trees (Intended to appear)