You might be surprised to find out just how often this cover gag has been used, although it seems to have been more popular at DC.
Let's start with my favourite. The cover to Wonder Woman #298 (December, 1982) is quite stunning. It brings a House of Mystery/Secrets vibe to a superhero title. Frank Miller was a terrific cover artist, and did created some truly remarkable images for both Marvel and DC. I think Dick Giordano was a good inker for him and I wish they had worked together more often.
Flash #186 (March, 1968) is another great one. This is the kind of Silver Age cover that would have intrigued any 10 year old on the planet. Ross Andru pencilled a ton of great Flash covers over the years. His sense of design is terrific. For another, rather gruesome Flash skeleton cover check out Rich Buckler's cover to #258.
The wonderful Jonah Hex Spectacular told us how our favourite bounty hunter would spend his post-living years. In fact the GCD Indexer stated "Lots of loose plot ends left hanging, including the fact that Jonah's death has been written already." All of that said, I still really dig the cover to Jonah Hex #92 (August, 1985). I am not always a huge fan of Denys Cowan, but his stuff looks really good inked by Klaus Janson. This is a fitting image for the final issue of a series that saw a ton of Four Colour death.
Alas, poor Clone, I knew him well. Or at least I though I did. The never followed the whole revisit to the Clone Saga in the mid-90s, so I don't have a clue how things turned out. In any event, the cover to Sensational Spider-Man #2 (March, 1996) by Jurgens/Janson team is pretty terrific, especially when compared to the dreck Marvel was putting on shelves during that era. It is a single image. There are no ridiculous captions. There are no mutants. There are not pneumatic babes. How did this get back the editors?