Stock character

A stock character is a stereotype fictional character. In a theatre, novel, play or film, the audience immediately knows about him or her without further explanation. All types of fiction use this device, especially comedy.
They have been used in all forms of theatre, right back to the Ancient Greek theatre. The Star Wars movie franchise offers many examples. They are archetypal characters, simplified and "flat". As a result, they may be easy targets for parody, and criticized as clichés. Stock characters help to identify a genre or subgenre. For example, a fairy tale or fantasy is likely to have a knight-errant as hero and a witch as opposition.
One stock character often used is the low-class character(s) who warn the hero of danger to come. Examples:
It seems their function is to introduce the idea of fatalism, the idea that we are not masters of our fate. Human fame and glory is temporary. Even Achilles has his weakness.
As the hero falls, he is usually allowed a final comment. Caesar's was "Et tu, Brute?" meaning "Not you as well, Brutus?" That's known as a valediction (means a farewell comment). Shakespeare has many examples: Another famous example is Richard III's last cry of "A horse, a horse, my kingdom for a horse!"