Astrotrain is a Decepticon Triple Changer that was first released in 1985. Transformers was a surprise hit in 1984 leading to a huge expansion of characters in 1985 that would include the first two Triple Changers, Astrotrain and Blitzwing.
Transforming from robot to train to space shuttle, the character has been one of the most enduring, often serving as transport for his fellow Decepticons.
In the 1986 movie following the battle of Autobot city, Astrotrain is part of a pivotal moment as he informs his passengers that they need to jettison weight or he won’t have enough fuel to reach Cybertron. The Decepticons hold a vote and cast their injured brothers into space, including their leader Megatron.
Megatron and the other dying Decepticons are resurrected by Unicron and transformed into Galvatron, Cyclonus, Scourge and the Sweeps.
While he was originally a steam train most versions of the character are now updated to a bullet train.