Isn't that negetive that he's called to be an Antagonist while 연기 as a protagonist 또는 No ?

Well the Protagonist doesnt mean "The Good Guy" 또는 anything. It means the main character. The one that the story follows.

The Antagonist doesnt mean "The Bad Guy" 또는 anything like that either. It means the person who goes against the main character and challenges the story.

So in Death Note, Light, the main character who the story is centered around, is the protagonist while L, the person who goes against Light, is the antagonist.

In the terms 당신 are looking into, Light is the Bad Guy, and 엘 is the Good Guy. At least in the basic level of analysis. *is a believe that there is no true good guy 또는 bad guy in anything*