Mason

Mason is a fictional character of the Grove Street trilogy who appeared as the primary antagonist in Grove Street 3: Never Back Down.

History
As the nefarious leader of the Millwall football hooligan gang, Mason cements himself as the notorious figure within the London underworld and it's local football hooliganism. His reputation is often escalated by his perpetual victories against multiple local rivals within cage battles - particularly against Green Street Elite, the firm of Millwall's arch-rivals West Ham United. Prior to the events of the film, a previous battle between both sides culminated with Mason ruthlessly killing his rival Joey Harvey.

This inevitably gains the attention of Joey's older brother and the film's protagonist - Danny Harvey - who returns to London to investigate the cause of Joey's death. As the ex-leader of the GSE, Danny reluctantly reprises his past role in order to reinstate the already-weaken GSE back into its former glory - thus gaining more info regarding Joey's murder as the truth gradually comes into fruition. Danny's presence along with the GSE regaining their uprising reputation soon delivers the attention of Mason himself - leading to both factions recurrently clashing with one another. At this point, it is revealed that Mason is posing as a high-ranking policeman known as "Derek Hunter" to cover up his true persona. He appears as the false superintendent of Victor, a retired GSE member who is also investigating Joey's death as well as getting himself involved with Danny's case. Upon discovering both issues, Mason takes the opportunity to meet with Danny face-to-face and deceives him into believing that Joey's best friend Gilly was the one who killed him due to his recklessness. This leads to Danny confronting and attacking Gilly up until the latter explains the truth behind Joey's murder.

Now aware of the truth behind his brother's death, Danny contacts Victor and persuades him into confronting Mason for the final of the cage confrontation between the GSE and Millwall - which he does by the time the truth about Mason killing Joey is uncovered. With this revelation, Mason no longer hides his double life façade towards Victor and vows to "smash his face in" as both sides prepare for their last battle. During the fight, Mason overpowers Victor before engaging Danny in a one-on-one brawl. He gets the upper hand and comes close to defeating Danny when he begins to taunt him over Joey's death, which provokes Danny into turning the tables and overpowering Mason - virtually beating him to death until the GSE coach restrains Danny, who eventually stands down in realization that he's not evil compared to Mason. As the GSE celebrate their victory over Millwall, both sides quickly retreat as the police arrive to scare the crowds and hooligans away as the fight is within a restricted area. With Mason too injured to flee in time, Victor promptly has him arrested for Joey's murder as well as "everything else" - implying his awareness of Mason's other nefarious activities during his reign.

Trivia

 * Mason is arguably the most evil antagonist to ever date in the Green Street trilogy.