Cop Killer

A Cop Killer is, as the title suggests, a person who kills at least one person working in the local police force or law enforcement agency. Usually, when a cop or agent is murdered, the rest of the police force/agency makes hunting the perpetrator down a top priority, as the officers intend for their colleague's death to not go unpunished. In the course of history, the term 'Cop Killer' has become more of a general identification for anyone who works in some sort of law enforcement field, such as a federal agent or a security guard.

On Criminal Minds
''Usually, whenever a policeman or agent is killed on the show, it is usually incidental and not intentional. One example of the contrary is Animal. Some known cop killers on the show include:''
 * Adrian Bale ("Won't Get Fooled Again") - Immediately before his arrest, Bale tricked six of Gideon's colleagues at the FBI to infiltrate a building storing a hostage and a bomb. Bale still had the trigger to said bomb and detonated the weapon, killing the hostage and all six FBI agents.
 * Phillip Dowd ("L.D.S.K.") - Dowd sniped a policeman who leaked information of the investigation to the press, as he was being arrested under suspicion of being the unsub.
 * Vincent Perotta ("Natural Born Killer") - Some of Vincent's victims have been seen to be policemen. Vincent also attempted to kill an undercover cop, but he was rescued.
 * Ted Bryar ("Derailed") - While undergoing a psychotic episode aboard a passenger train, Ted grabbed the gun of a security guard venturing onto his passenger car and used it to fatally shoot him.
 * Cally's Tribe ("The Tribe") - While approaching the house of their soon-to-be victims, the Minton family, the tribe was forced to kill a policeman who was assigned to spy on the family.
 * Will Sykes ("A Real Rain") - In his plan to copycat a series of vigilante murders, Sykes fatally shot an undercover policeman, believing him to be a criminal attempting to attack him.
 * Bruno Hawks ("Secrets and Lies") - Bruno murdered a CIA agent when he refused to give him important information. Later, he killed another agent when she tried to frame him.
 * Militant Islamic Society ("Lessons Learned") - The group rigged a house with explosive bombs that successfully detonated, successfully killing one DEA agent in the process when he, the BAU, and a few other DEA agents attempted to go inside.
 * Roy Woodridge ("Distress") - While undergoing a psychotic break induced by post-traumatic stress disorder, Roy killed a construction site security guard. The break was triggered by the sound of a gunshot fired by the guard when the latter attempted to scare off vandals.
 * Francis Goehring ("Identity") - When he was cornered by three policemen, Goehring decided to commit a suicide attack, which only succeeded in killing one of them along with himself.
 * Jason Clark Battle ("Lucky" and "Penelope") - While stalking Garcia after finding out she survived him, Battle calmly walked towards a policeman assigned to protect her and Morgan and shot him twice in the chest.
 * Owen Savage ("Elephant's Memory") - After killing Rod Norris with a planted bomb, Owen waited for his father Lou, a police deputy, to respond to the bombing. When Lou and another policeman were the first officers to respond, Owen attacked them with an assault rifle he stole from Lou, killing both.
 * Steven Fitzgerald ("In Heat") - At the beginning of the episode, Steven murders a gay man he befriends, Charles Luvet, who was a vacationing New Orleans police detective.
 * New York Terrorist Cell ("Lo-Fi" and "Mayhem") - The cell mortally wounded a New York police officer with a SUV bomb, and then, during its attempted bombing of a hospital, one of its members shot four Secret Service agents dead. The New York police officer later died of her injuries.
 * Armando Salinas ("Catching Out") - With a railroad security guard searching for him, Armando boards a train and waits for the guard to come aboard before stabbing him to death with a rail spike.
 * Animal ("Brothers in Arms") - Animal dedicated most of his killings to murdering those he saw as figures of authority: police officers. He successfully managed to kill four.
 * George Foyet ("Omnivore", "...And Back﻿", "Nameless, Faceless", and "100") - In Omnivore, when Morgan and a Boston policeman raided one of his homes to look for him, Foyet ambushed the latter outside and killed him by apparently stabbing him to death. In 100, in order to find out where Haley and Jack Hotchner are, Foyet attacks the U.S. Marshal assigned to protect them to gain information from him. In the process, the U.S. Marshal was fatally wounded and died en route to the hospital.
 * Darrin Call ("Haunted") - Whilst attacking people at a pharmacy during a psychotic episode, one of the people Darrin killed was a bank guard, who tried to shoot him with his gun, but it was stolen by Darrin and used to fatally shoot him twice.
 * Dale Schrader ("Retaliation") - When his partner Joe Muller sent the police cruiser containing him, Prentiss, and a police detective crashing down a hillside as part of an escape plan, Dale recovered from the crash quickly and strangled the detective to death before stealing the keys to his handcuffs.
 * Connor O'Brien ("Public Enemy") - After killing a flower salesman at a marketplace, Connor stayed behind at the crime scene, apparently to feed off of the crowd's fear, when he was spotted by a policeman he knew while attempting to flee, forcing him to stab him twice in the neck and collar when he tried to detain him.
 * Ronald Boyd ("A Rite of Passage") - Devolving into a spree killer, Boyd lured his boss into a secluded area before shooting her to death. Then, while attacking the Lugo Cartel with a shotgun, he murdered the deputy accompanying him with a revolver when he witnessed the massacre.
 * Billy Flynn ("Our Darkest Hour" and "The Longest Night") - After luring Morgan and Detective Matt Spicer into a trap using Spicer's sister and daughter in Our Darkest Hour, Billy knocked Morgan out briefly before goading Spicer into surrendering by threatening to shoot Ellie. When Spicer caved in to the demands, much to Morgan's distress, Billy shot him in the chest at point-blank range.
 * Hanley Waters ("Hanley Waters") - After robbing a liqour store in 2010, Waters led authorities on a high-speed car chase that ended abruptly when he crashed into the car of future spree killer Shelley Chamberlain, killing her son Damien. During the incident, Waters became responsible for the death of a policeman; the cause of this fatality currently remains unspecified.
 * Shelley Chamberlain ("Hanley Waters") - While in the middle of a psychotic break, Shelley shot and killed a mall security guard in a blind fit of rage when he tries to escort her out of the building. Later on, she injured two police officers at a nearby roadblock.
 * Chloe Donaghy and/or Richard Gerace ("It Takes a Village") - During their operation of revenge against Ian Doyle, Chloe and Gerace infiltrated the house of Doyle and Donaghy's long-lost son Declan, which was currently being guarded by two FBI agents, both of whom were killed in the attack.
 * Luke Dolan ("Dorado Falls") - As part of his mission to infiltrate the BAU headquarters, Dolan murdered an FBI police officer for his uniform and security pass.
 * The Face Cards ("Hit" and "Run") - During the Capital Bank robbery, one of the group's members fatally shot a security guard. Soon after, another member shoots an arriving officer in the head while attempting to flee with his accomplices. Later, during the resulting hostage situation, the third member would go on to execute an FBI agent when the agent tried to shoot him.
 * John Myers ("The Silencer") - While escaping from an ambulance following a crash, Myers fatally asphyxiated a prison security guard who was in the vehicle and was the only other survivor of the crash.
 * Willie Kestler ("Perennials") - After shooting and killing a hospital clerk in a fit of rage, Kestler then shot a security guard in the head when he attempted to intervene.
 * Tory Chapman ("Pay It Forward") - As part of his scheme to expose the liars of his hometown, Tory lured out a Sheriff's Deputy into a secluded location, shot him execution-style, and decapitated him post-mortem. The Deputy was targeted for illegally maintaining a second family in secrecy.
 * Wallace Hines ("The Inspiration" and "The Inspired") - While holding several people hostage at his workplace, Wallace was confronted by a shopping mall security guard, who held him at gunpoint and ordered him to drop his own gun. Though Wallace dropped a meat cleaver he was holding against one of the hostages, he then shot and killed the guard with his pistol before fleeing.
 * Gulino's Soldiers ("The Return") - During their attacks, the soldiers specifically targeted locations that were known to be frequented by officers for the Chicago Police Department. Only one of their attacks was successful in claiming the life of an officer: Trevor Madison committed a suicide bombing at an intersection supervised by traffic cops, killing one of them.
 * The Killer Woodsman ("Blood Relations") - During a raid into his house, a SWAT agent accidentally triggered a trap made by the Woodsman while opening a door; a blade swung down and impaled the agent, killing him.
 * Owen McGregor ("Angels" and "Demons") - In order to spark a shootout between Sheriff's Deputies and Justin Mills, McGregor shot and killed Sheriff Peter Coleman, who was also his target in order to cover up his corrupt activities. Later he murdered his accomplices, Deputies Marty Bennett and Vicky Lorenzana after they failed to kill Rossi and Blake.
 * Benton Farland ("Amelia Porter") - In need of a more suitable weapon than a knife, Benton broke into a psychiatrist office building and stabbed a night security guard to death, later stealing his firearm and using it in his later crimes.
 * Daniel Dryden ("Killer Profile") - As he prepared to kill his eighth victim (via premature burial in a coffin), Daniel was spotted by a police detective, who apparently pieced together that he was the killer, forcing him to kill the detective and knock him on top of the coffin the victim was still in before filling the hole.
 * Donnie Mallick ("Nelson's Sparrow") - A serial killer and abductor James Gideon and David Rossi investigated in 1978, but never caught. After the death of his 37 year captive Tara Barnett from cancer, he dumped her corpse in the same manner he had his previous victims which caught the attention of Gideon, who decided to conduct his own independent investigation and concluded the killer had returned. However Mallick recognized Gideon from an old newspaper clipping he had kept from the 1978 investigation and realizing the retired agent was onto him and decided to kill him to prevent Gideon from alerting his former colleagues in the BAU, Mallick murdered Gideon with a high-powered rifle from outside Gideon's cabin then entered the cabin to taunt Gideon before his death allowing Gideon to see his face before killing him with a shot to the head.

Real World

 * Charles Whitman, murderer of Officer Billy Speed during the University of Texas sniper attacks
 * Eric Robert Rudolph, murderer of Robert Sanderson in an abortion clinic bombing
 * Timothy McVeigh, convicted of murdering eight federal agents in the Oklahoma City bombing
 * Lee Harvey Oswald, assassin who murdered of Texas Patrolman J.D. Tippit
 * Larry Phillips, Jr. and Emil Mătăsăreanu, murderers of bank guard Herman Dwight Cook
 * Christopher Dorner, killed four people, including two police officers and a Sheriff's Deputy
 * Tamerlan and Dzhokhar Tsarnaev, murderers of MIT police officer Sean Collier
 * Mark Essex, killed nine people, including five police officers, in a murder spree that spanned eight days
 * Bobby Davis and Jack Twinning, perpetrators of the Newhall massacre
 * Richard Poplawski, perpetrator of the Pittsburgh police shootings
 * Lovelle Mixon, perpetrator of the Oakland shootings
 * Maurice Clemmons, perpetrator of the Lakewood police officer shooting