Dimetrodon the actor.

In 1959 a version of Journey to the Center of the Earth was released that included a scene where a "Dimetrodon" and his family chased and attacked the main characters. These Dimetrodon were made out of some clever prosthetics and live iguanas running about on screen. While obviously not the real animal it was done fairly well for what it was and it's kind of funny as well.The "attack" begins at the 6:50 mark of this first clip and ends in the beginning of the second clip:

Dimetrodon has been updated since then thanks to computer graphics and set loose on its Permian prey Edaphosaurus in Walking with Monsters from the BBC.

But, more importantly for paleontologists, Dimetrodon are still being found very nearly complete and well articulated in Texas by Robert Bakker's dig team from the Houston Museum of Natural History. This video from last season's dig shows what kind of things they are finding.