Whenever a sentence directly addresses your readers, you must use a comma to notate it. The name of the person you are addressing is not actually part of the main clause; the name makes it clear that you are directing the clause to a specific person.
When the direct address appears at the beginning of the sentence, a comma is necessary immediately following it.
Example 1: Spiderman, your webs weave a complicated path.
When the direct address appears at the end of the sentence, a comma is necessary immediately preceding it.
Example 2: That height of the building made saving the girl seem impossible, yet you made it look easy, Superman.
When the direct address appears in the middle of the sentence, commas should offset both sides of the direct address.
Example 3: On you, Green Arrow, the color green looks much more appealing.
Sometimes, leaving the comma out that implies a direct address can even create confusion.
In the above example, omitting the comma that identifies the direct address changes the entire meaning of the sentence. With the comma, it is clear you are asking Wonder Woman, specifically, if she would like to eat. Without the comma, you are asking your readers as a whole if they want to eat Wonder Woman. While many of your readers may find Wonder Woman attractive, it is unlikely that they want to have her for a meal.