Starscream is a character in the Transformers
universe(s). He appears in almost every incarnation of the series, the most oft-recurring character type after Optimus Prime
. He begins most series as Megatron's second in command, but is not content with that position, desiring to replace Megatron as leader of the Decepticons. But the enemy of our enemy is not our friend in this case: he sees humans as worthless insects, and is as dedicated to the destruction of the Autobots as any other Decepticon.
His reasons for wanting to overthrow his leader can vary from one incarnation to the next - sometimes he's simply power-hungry, and sometimes he truly believes he would be a better leader for the Decepticons. Also different from one incarnation to the other is just how effective he is at it - and how long he gets away with it before being blasted to smithereens by his leader. It's fortunate that another recurring trait of Starscreams is that they tend to be very bad at staying dead.
He's often nicknamed 'Screamer by the fandom
Most versions of Starscream turn into fighter jets, and wield small arm-mounted blasters.
Megatron screams his name in rage, Khan-style, at least once per incarnation.
"Don't worry, I'll tell them all you went offline valiantly - just after you named *me* as your successor!" -Starscream, A Bridge Too Close