Thanks for the question.
It depends. Portraying violence, whether fictional or real, is not in itself a sin, nor is the viewing of it. That being said, if the violence were being portrayed for some immoral purpose such as to provoke violence, de-sensitize viewers to violence, to propagandize for evil intents, or other reasons, then participation in such viewing would be sinful.
The use of violence in entertainment requires careful discernment on behalf of the viewer to insure that one is not participating in some harmful activity.
So, ultimately, it is a matter of conscience and good discretion. If the violence you consume is glorifying evil acts for their own sake, stay away.