The Thing is one of my favourite horror films. It stars Kurt Russell and is directed by John Carpenter.
It deals with a group of men at an antarctic outpost who one day witness norwegians in a helicopter attempting to shoot a dog running away. The Norwegians crash and the dog is taken inside. Little did they know that it was infected with Alien genetic material.

The alien(s, because each cell is its own "being") gradually take over more and more people, and the film escalates into some very memorable moments such as the blood test scene.

Worth watching who ever you are...and the DVD just plain rules!

Memorable Scene:.

It involves identifying who of the remaining people are human, and who are now "Things". Kurt Russell achieves this by taking blood samples from everyone, and heating a piece of wire with a flamethrower. He then puts the red hot wire into the blood to see what happens. This is on the premise that all parts of the "thing" are in fact entities in their own right, with a desire to carry on living.

Also sports Donald Moffat speaking one of the best lines in cinema, "If it's ok with you gentlemen...I'd rather not spend the rest of this Winter, TIED TO THIS FUCKING COUCH!".

A Classic.