Astrotrain is the name of three fictional characters in the various Transformers universes. All are Decepticons who can assume the form of a space shuttle.
Transformers: Generation 1
Astrotrain is a Triple Changer who can assume the form of both a steam locomotive and a space shuttle.
Astrotrain's Marvel and Dreamwave bios both state that he loves using his Triple Changing abilities to create confusion among his enemies, enjoying the fear in their eyes in the moments before he destroys them.
Astrotrain first appeared in season 2 and was a part of Megatron's forces on Earth. Although typically a secondary character, Astrotrain was a main player in two episodes. In the episode "Triple Take-over", he and fellow Triple Changer Blitzwing froze Megatron and Starscream and took leadership of the Decepticons for themselves. Leading an army of drone-like locomotives, he was defeated and forced to return command to Megatron at gunpoint.
Astrotrain was seemingly let back into the Decepticons after this, being sent alongside Blitzwing in "Prime Target" to forge an alliance with the big-game hunter Lord Chumley, although Chumley had no interest in the Decepticons, merely wishing to hunt the ultimate prey, Optimus Prime.
Like other Transformers in the animated series, Astrotrain's size changed greatly in his various forms. His primary role was transporting Decepticons as a space shuttle or train. However, in robot form, he was no larger than an average-sized Transformer.
One of Astrotrain's most prominent actions appeared in the episode "God Gambit". The Autobot, Cosmos discovered an energy source on Saturn's moon Titan, but was shot down by Astrotrain and disabled. Upon discovering a large deposit of energy crystals, Astrotrain (accompanied by Starscream and Thrust) persuaded Titan's inhabitants, the Talarians, to worship him as a god, subsequently using them as slaves to mine the crystals. The disabled Cosmos, being held prisoner, managed to contact the Autobots, thanks to a Talarian rebel who reactivates his communicator. Omega Supreme, with Perceptor and Jazz aboard, arrived and eventually drove off the Decepticons but not before Astrotrain destroyed the crystals, proclaiming if he can't have them, nobody can.
In The Transformers: the Movie, Astrotrain was also present at the Battle of Autobot City but was not wounded. He transported the defeated Decepticons back to Cybertron following their defeat by Optimus Prime. It would turn out he was not strong enough to carry them all. Several of the weaker Decepticons were literally thrown off of him, only to be found and changed by Unicron. Of note, his shuttle size changed greatly from moment to moment - Starscream is shown as being nearly as high as his door (which is nearly to the ceiling), but less than a minute later, Devastator is able to stand inside him. After they arrive on Cybertron, Astrotrain is shown to be the one crowning Starscream during the coronation scene, although it seems that he is slightly shorter than Starscream. Like the rest of the Decepticons, Astrotrain accepts Galvatron's leadership without question.
He would continue to make sporadic appearances throughout season 3.
Prime Wars Trilogy