Title: THE THING#24 by Mark Gruenwald (I think; writer) and ____________(artist)
Synopsis: After the Miracle Man's attempt to manipulate the Rhino, initially successful, fails in the end after the Thing reasons with the Rhino, the Miracle Man attempts a getaway. One of the passengers on the bus many of them were on at the beginning of the story, who looks like a hippy, shoots the Miracle Man with a shotgun containing explosive bullets, declaring, "Justice is Served!"
Is it key to the overall Scourge storyline? No. Just a random hit.
Does it tie in to the rest of the issue? Yes. Scourge is present in disguise throughout as a bus passenger, only striking near the end. His victim was the main villain of the story (aside from the Rghino, who was just a dupe)
Comments: This is the oldest of Marvel's villains to get slain, first appearing in Fantastic Four#3.
Scourge does not attempt a hit on the Rhino in this story. There are probably two reasons for this: it's unlikely that the bullets could penetrate the Rhino, and Scourge probably didn't want to alert the Thing, who was physically close to the Rhino both during the rampage and after the Rhino calmed down.