Fictional comedy throws funny, unrealistic characters into extreme situations. For example, Wile E Coyote goes to extremes (i.e., strapping himself to a rocket) in order to catch the Road Runner for dinner.
Standup comedians like Robin Williams often take real-life people and events and retell the stories in a comical manner.
The Greeks were possibly the masters of fictional tragedy. Stories like Oedipus Rex tell of noble heroes brought to their knees by fate or pride. The stories often end with the death or defaming of the hero.
Tragedy takes place everyday, even when no one sees it. The neglect of a child to the assassination of a president are both tragic, real-life events.
Sometimes comedy and tragedy combine. Lemony Snicket's "Series of Unfortunate Events," tells the story of three unlucky orphans, but combines the text with witty puns and outright sarcasm. Though the events may be depressing, the inflection of the storyteller can change the perceived emotion.