The Snake Runner appears in the episode "Billy's Bucket List." It bites at Finn and Canyon as they ride past on Billy's motorcycle. It then chases them, brandishing a short sword in each arm. When it catches up, it lunges at Canyon, who ducks and punches it. It is last seen lying motionless in the desert. Despite its relatively spindly legs, the Snake Runner can run faster than Billy's motorcycle.
The Snake Runner is very large in comparison to Canyon. It has red eyes, sharp teeth, light-yellowish green scales, and four skinny limbs, the front two of which it uses to wield two short swords.