Masticophis flagellum is a species of non-venomous colubrid snakes commonly referred to as coachwhips or whip snakes. There are seven recognized subspecies.

Coachwhips range throughout the southern United States from coast to coast. They are also found in the northern half of Mexico. Typically they are found in open grassland type habitat, but can also be found in lightly forested areas.

Coachwhips are a diurnal snake (active in the daytime), and actively hunt and eat lizards, small birds, and rodents. They tend to be high strung, and often bolt at the first sign of a potential threat. They are extremely fast moving snakes. They are curious snakes with good eyesight, and are sometimes seen raising their heads above the level of the grass or rocks to see what is around them.

The primary myth concerning coachwhips is that they chase people. This likely arises from the snake and the person both being frightened, and both just happen to be going the same way to escape. Coachwhips are very fast snakes, and can often move faster than a human, thus giving an impression of aggression, should they move toward instead of away, when really they are just going in the direction they believe will lead them to safety fastest. Another myth of the rural southeastern United States is of a snake that when disturbed, would chase a person down, wrap him up in its coils, whip him to death with its tail, and then make sure he is dead by sticking its tail up the victim's nose to see if he is still breathing. In actuality, coachwhips are nowhere near strong enough to overpower a person, and they do not whip with their tails, even though it is long and looks very much like a whip. Their bites are also harmless.