Usually done in a humorous or satirical tone, comics created as parody highlight the contradictions, idiosyncrasies and/or hypocrisies of their subject matter. They are thematically related to, but do not fall within the concept of Alternate Universe story lines. Most often parodies are one-shots and as an art form they may be just a single image to create a visual joke or "sight-gag".
Parody and especially self-parody is common in the comic industry for entertaining the reader. A comic book parody might be done to make fun or "send-up" a long established character or even the publisher itself, while a continuing series might use parody extensively to add supporting humor. Much of the meaning from parody relies on the reader being familiar with the subject matter, so the context is often taken from pop-culture, current events, or specific cultural themes.
Political cartoons are one of the oldest comic art forms still being read today that are entirely based on satirical parody.