Star Scream

Starscream starts out as a neutral being neither Autobot nor Decepticon. He at some point sides with the Autobots and is charged with defending an orbital spacestation that manufactures Energon and contains Dark Energon by Zeta Prime and Jetfire. After meeting Megatron, he decides to join his insurrection of Decepticons as leader of the aerial forces, plotting to ultimately betray him when the time is right. He is the leader of the Seekers.