Alonzo Harris is the main antagonist of Training Day. He is a cop who has sunk far too deep into the criminal underworld, corrupting himself in the process.
He is portrayed by Denzel Washington.
L.A.P.D. Detective Sergeant Alonzo Harris has sunk so deep into the depths of his line of work that he has corrupted himself to the point where his own life has become the target of a foolish debt to be repaid. And on this particular Training Day, Alonzo has just begun to mentor young Jake Hoyt, a rookie cop who still possesses the ideals of every bright-eyed rookie police officer.
As Alonzo exposes Jake to the harshness of the streets where many a drug deal takes place, he also reveals his own questionable tactics in fighting the criminal element, whether that means intimidating the "animals" at will or misrepresenting themselves with fake search warrants. Alonzo also manipulates his new student, going so far as to hold a gun to his head to get him to smoke drugs, which turns out to be a clever blackmail device later on.
However, as the subsequent events begin to reveal his motivation (a large debt is owed to Russian gangsters by the end of the day), Jake's morals collide with Alonzo's master plan. With the exception of his girlfriend or son, neither friend nor foe will stand in his way, and this constant deception, distrust, and disrespect for others leads Alonzo to his downfall. At the end of the Day, honor indeed prevails and Alonzo gets what he deserves. As he is trying to escape to Los Angeles International Airport, he is ambushed by the Russian mafia and brutally killed with machine-gun fire.