Isn't that negetive that he's called to be an Antagonist while Актёрское искусство as a protagonist или No ?

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

The Antagonist doesnt mean "The Bad Guy" или 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 Ты are looking into, Light is the Bad Guy, and L is the Good Guy. At least in the basic level of analysis. *is a believe that there is no true good guy или bad guy in anything*