Shockwave

Shockwave was a mighty Autobot Warrior that was almost a good friend to every Autobot until the Demon Sith Lord Darth Grievous has turned him evil with the Dark side.

History
Being one of the Autobots most best soldier he knows that every enemy like the Sith must be destroyed. In a climatic battle he worked with Powerglide until Darth Grievous captures him and turned him into the most loyal servant of the Sith. In order to protect the universe Powerglide had to kill Shockwave to preserve the universe.