What is a tragedy?

From Free Dictionary.com:

trag·e·dy  (trj-d)

n. pl. trag·e·dies

1.

a. A drama or literary work in which the main character is brought to ruin or suffers extreme sorrow, especially as a consequence of a tragic flaw, moral weakness, or inability to cope with unfavorable circumstances.

b. The genre made up of such works.

c. The art or theory of writing or producing these works.

2. A play, film, television program, or other narrative work that portrays or depicts calamitous events and has an unhappy but meaningful ending.

3. A disastrous event, especially one involving distressing loss or injury to life: an expedition that ended in tragedy, with all hands lost at sea.

4. A tragic aspect or element.

This website explains the literary form of tragedy according to Aristotle.

What modern day stories (books, movies, television shows) do you consider to be tragedies?