Scourge is Galvatron's implacable tracker and leader of his own cadré of huntsmen, the deadly Sweeps. He was created by Unicron from the remains of a dead Decepticon. Immensely powerful like all the Unicronian Decepticons, arrogance is his only true weakness. Despite being quite powerful in his own right, Scourge generally acts as a near subordinate to Cyclonus, and, despite his leadership of the Sweeps, is generally content to take orders from others. Scourge tends to grumble and complain a bit (a habit sometimes shared by his Sweeps).
But then again, you'd also complain if your boss spent so much time beating you up, wouldn't you?
In the Kingdom Hearts Unlimited Saga, Scourge appears as a recurring minor antagonist, mostly as one of many new Decepticon warriors created following the failed battle of Autobot City, and a staunch supporter of Galvatron in his alliance with several villain organizations.