Is exactly what you would think it is. A comic covers that pays homage to a popular form of media It’s normally homage to a very iconic cover.
Homage to other comic book covers
The Killing Joke is probably one of the most iconic Batman covers and one that is constantly used.
Amazing Fantasy #15 is one of Marvel’s most iconic cover’s that has been used constantly with Spider-Man holding a host of different people. The most iconic one has Peter holding Stan Lee.
Amazing Spider-Man 300 is one of the most popularly done across the board. Spawn is made by Image but as you can see. A very beautiful homage.
Homage variants can also go far beyond the comic book world.
This is Static Season #4 Nikolas Draper-Ivey variant cover. It is a homage to animated movie Akira.
This is Stray Dogs #4 4th print. This was a horror based comic book. So in many of the printings the covers were dedicated to famous horror movies. This one I had to get, because 28 Days Later is one of my favorite horror movies of all time.