Hudun Pao, "crouching tiger" or "sitting tiger," is an ancient Chinese siege machine which launched a projectile from a sling at the end of its arm, which was mounted on a rigid triangular frame.

The Sitting Tiger is an early version of the traction trebuchet, which means that it was powered by the pulling force of men on ropes attached to the short end of the arm. The engine was smaller and had shorter range than its larger counterweight-driven counterparts, but this made it far more portable.