Even more vital than Star Destroyers in making a Star Wars film have the right feel are TIE fighters. With their unmistakable howl as they swoop down to attack, these one-man fighters cast fear into the hearts of the Empire's enemies. George Lucas originally called the crafts TIEs because of their similarity in shape to bow ties. However, the acronym was later said to stand for Twin Ion Engine, reflecting the nature of the fighters' propulsion systems. Little is explicitly stated on screen about these fighters, but much has been inferred and incorporated into the Expanded Universe- for example, the shape of the wings makes landing on a planet difficult, restricting the fighters to launching from and returning to Star Destroyers or space-based facilities. TIEs are the cheaply produced workhorses of the Galactic Empire. However, the utilitarian nature of the fighters seems to lend itself easily to modification, with TIE bombers and TIE Interceptors being common variations from the basic model. Since TIE fighters were seen in the teaser for The Force Awakens (with a modified look), this iconic ship can now be said to have appeared in four of the seven "main" films. Few other starships can make the same claim...