Who is called a serious piece of writing whose ending always sorrowful?

A serious piece of writing whose ending is always sorrowful is called a tragedy.

Here's why:

* Serious Subject Matter: Tragedies typically deal with serious themes like death, loss, fate, and the human condition.

* Downfall of the Protagonist: The main character, often a noble or admirable figure, experiences a downfall or tragic end.

* Sorrowful Outcome: The ending of a tragedy leaves the audience with a sense of sadness, pity, and even catharsis (a release of emotions).

Some famous examples of tragedies include:

* Hamlet by William Shakespeare

* Oedipus Rex by Sophocles

* Macbeth by William Shakespeare

* Romeo and Juliet by William Shakespeare

Let me know if you have any other literary questions!