The Caterpillar 797 is a series of off-highway, ultra class, two-axle, mechanical powertrain haul trucks developed and manufactured in the United States by Caterpillar Inc. specifically for high-production mining and heavy construction applications worldwide. In production since 1998, the 797 series represents Caterpillar’s largest, highest capacity haul trucks. The current, third-generation model, the 797F, offers one of the largest haul truck payload capacities in the world, up to 400 short tons (363 t) and has the highest payload capacity among mechanical drive haul trucks.

Haul trucks are off-road, heavy-duty dump trucks specifically engineered for use in high-production mining and exceptionally demanding construction environments. Most are dual axle; at least two examples of tri-axles were made in the 1970s. Haul trucks are denominated by their payload capacity, by weight.