The Incredible Hulk #338 (1987)

"Mercy Killing"  Written by Peter David, pencils by Todd McFarlane, inks by Jim Sanders III. Cover pencils by Steve Geiger, inks by Bob McLeod.  Bruce, Rick and Clay are on the run from SHIELD trying to find a cache of gamma bombs.  The Hulk fights off the mysterious Mercy, who tries to end his doomed existence by doing him the favor of killing him.

Key book; first appearance of Mercy, interior art by Todd McFarlane. Near mint condition.