In the show the 20-something brothers travel the highways and byways of North America in search of their missing father. Along the way they encounter various evil spirits with which they do battle.
It's kind of a family tradition.
Now in its second season, the show's other big star is, of course, the big black American muscle car that carries the brothers on their exploits.
Many people have asked us what kind of car the Winchester brothers drive. We can report the car, owned by older brother Dean, is in fact a four-door, 1967 Chevrolet Impala.
When the car was smashed at the end of the first season, the show's creator Eric Kripke revealed he was inundated with letters from fans wanting to know if it was going to make a return?
“When I was originally writing the show I wanted to give the guys an American muscle car,” Kripke said.
“My first choice was a '65 Mustang. My neighbour said it had to be a '67 Impala because you can put a body in the trunk.
“He says, 'You want a car that, when people stop next to it at the lights, they lock their doors'.”
Five black Impalas are actually used in the production of the show. In the pilot episode, the car's huge trunk is revealed to hold a travelling armoury of weapons which the brothers use to do battle with supernatural forces.
The Impala has a Sedgwick County, Kansas (even though they are from Lawrence, Kansas) licence plate KAZ 2Y5, a reference to Kansas, the Winchesters' home state, and 2005, the year the show premiered.
The Impala has been nicknamed the Metallicar by fans of the show.
The Chevy Impala takes its name from the swift antelope found in herds on the grasslands of central and southern of Africa.
Introduced in 1958, the Impala was developed by GM's then chief engineer Edward Cole who later became president of the company. It began life as a concept car for the 1956 General Motors Motorama and at one time was the best selling full-size car in the US.
Introduced as a trim package, the sporty new model was unique with its six tail lights. It eventually became the best-selling car in the Chevrolet line-up and, in 1959, became a separate model in both two and four-door versions.
Continuing for a decade as the best-selling automobile in the US, Impala broke the record for sales with more than 13 million units sold.
The two-door Impala SS (Super Sport) is credited for the beginning of the muscle car era.
During the 1973 energy crisis, however, Impala sales plummeted and the car was redesigned to meet changing demands. The name continues to this day.
The 1967 model as featured on the show came with a choice of inline six-cylinder as well as the famous Chevy small-block and big-block V8s.
The big block V8s included a 325hp 396 cubic inch and 385hp 427 cubic inch units. It was available with a four-speed manual or three-speed turbo hydramatic auto in big block V8 form.