What is the function of an antagonist in a story?

The role of the antagonist is to create a direct conflict with the protagonist or main character of the story. The protagonist has a set goal to achieve in the story, and the protagonist is set to make it more difficult for them. Also, antagonist don't necessarily have to be evil, they simply work against the protagonist.

the penalty for defying creon's decree is death, as can be seen in the tragedy. if you do obey him however, all is forgiven