A modified bulldozer used by Marvin Heemeyer to rampage through a small town in Colorado in June 2004. The killdozer took one and a half years to build, using a Komatsu D355A bulldozer as a base which was then coated in concrete and steel plating one foot thick. Cameras made with three-inch bulletproof plastic were fitted to the outside to provide vision, and specialist HVAC systems were introduced to the cabin. The top was coated in oil to make it difficult for others to board the vehicle. Once Marvin entered the vehicle it was designed to be impossible for him to leave.

The systems built on the killdozer were remarkably effective, as three explosions and hundreds of ammunition rounds failed to have an impact once the rampage started. The destruction amounted to 7 million dollars in damage spread over 13 buildings, and took several hours. Nobody was killed except for Marvin himself, who committed suicide once the killdozer got stuck. It took 12 hours to cut through the armour of the vehicle and remove the body.