Scene Cover

Comic book Covers Always Lie, but every now and then, you find a cover that actually tells you what's in the comic by showing a scene that really takes place, with little or no deviation from an actual panel in the story. In other words, the art was taken from the actual panel itself. Of course, the scene can still be so out of context as to throw you off, bringing us back to Covers Always Lie, but there you are.

See also Cover Drop.

Examples of Scene Cover include:

Action Comics #1 has an iconic cover that has been parodied, homaged, copied and just plain stolen in almost every other visual medium. The image of Superman lifting the car is so associated with the character that each new iteration of the character will re-enact the scene, albeit often in different context. The artist made the cover by taking a panel from the interior story and blowing it up to fit the entire page.
A Silver Age Superman comic in which Lois dates an astronaut has a cover that shows Superman killing her in space: Although the scene was tweaked a little for the cover, it unfolded almost exactly as shown; except that Superman wasn't really trying to kill her, as the cover implied; he was snapping her oxygen tube because of some innocuous reason that This Troper forgets.
Watchmen's covers were extreme closeups of stuff from very early in the issue.
This is not solely limited to art; a popular convention on many, many fanfiction communities is to use an out-of-context quote from the story in place of a summary.
Marvel's Digital-Exclusive Comics tend to simply use a panel of the comic as the "cover", probably because they don't need to use the cover to attract people and it's cheaper than getting a cover artist for a cover that still applies under the previous reasoning.
Most of the Warrior Cats graphic novels show a scene from the volume, but they usually don't match an actual panel. The only one that has so far is Into the Woods.