In 'Black Mass' based on a true story, Whitey Bulger is the most prominent character. He was a key player in the criminal underworld. Johnny Depp's portrayal of him really stands out. There's also John Connolly, an FBI agent. Connolly's actions and his connection to Bulger are crucial elements of the story. His actions led to a lot of the events that unfolded, and his relationship with Bulger was a mix of loyalty and self - interest. There are also other characters who are part of Bulger's criminal gang or those in the law enforcement who were affected by Bulger's actions.
The main character is undoubtedly Whitey Bulger. He was a real - life criminal whose story is the basis of 'Black Mass'. Johnny Depp brought him to life on the screen with his intense performance. Then there's John Connolly. He was an FBI agent who got involved with Bulger in a way that was both unethical and ultimately very dangerous. Connolly thought he could control Bulger, but it turned out to be a huge mistake. There are also other supporting characters like members of Bulger's crew who were involved in the various illegal activities, and other law enforcement agents who were either trying to catch Bulger or were being manipulated by Connolly.