Apatosaurus

Apatosaurus (pronounced /əˌpætəˈsɔːrəs/), including the popular, but obsolete synonym Brontosaurus, is a genus of sauropod dinosaurs that lived about 150 million years ago, during the Jurassic Period (Kimmeridgian and Tithonian ages).

More real-life information: Apatosaurus at Wikipedia.

Jurassic Park Series
Apatosaurus is often seen in both novels, but in the movies they are replaced by Brachiosaurus.

Jurassic Park novel
After Dr. Alan Grant and his companions arrive at Isla Nublar they are brought to the Apatosaurus terrain. These dinosaurs are the first dinosaurs the group encounters. They walk elegantly like giraffes but have a dumb expression on their faces. The herd of Apatosaurs consists of 17 members.

The Lost World novel
By the time of the events of The Lost World the Apatosaurs also have regained the ability to reproduce. A herd of Apatosaurs roames in the river valley at the center of Isla Sorna. A herd of Parasaurolophus stayes close to the Apatosaur herd for protection.

The Lost World: Jurassic Park film
Apatosaurus was not in the movies. However, the dinosaur's skeleton was briefly seen in The Lost World; it could have been a herd that falled into a dead end and was killed.

Jurassic Park inspired games

 * Apatosaurus was planned to appear in the game Jurassic Park: Operation Genesis.
 * Apatosaurus is nr. 052 of the Herbivore Threes that can be created in Jurassic Park III: Park Builder.