Assassin

Not to be confused with the term "hitman" An assassin is someone who kills, or at least attempts to kill a person prominently known to the public. Their reasons for doing so vary, though the most popular motive is for political reasons.

Types of Assassins

 * Type 1 assassins are defined as being motivated by high-profile reasons, like politics or religion. John Wilkes Booth was motivated to assassinate Abraham Lincoln as means of upturning restored order to the U.S. after the fall of the Confederacy.
 * Type 2 assassins are defined as being egocentric and motivated to commit their crimes in order to gain recognition. Charles Guiteau was egocentric and motivated to assassinate James A. Garfield after his requests to become a U.S. ambassador were turned down.
 * Type 3 assassins are defined as being psychopaths and sociopaths whose methods were disorganized. Charles Manson was a sociopath who ordered the members of his Manson Family to kill everyone in 10050 Cielo Drive, including actress Sharon Tate in hopes of starting a race war.
 * Type 4 assassins are defined as being delusional. Mark David Chapman was stated to be delusional at the time of his murder of John Lennon.

On Criminal Minds

 * Maggie Lowe ("Somebody's Watching") - Began executing everyone connected to Lila Archer, whom she had a delusional obsession for. Because of her delusional state, she is classified as a Type 4 assassin by the BAU.
 * New York Terrorist Cell ("Lo-Fi" and "Mayhem") - Enacted an elaborate scheme to kill an unspecified but high-ranking politician by infiltrating the hospital he was being treated in, and blowing it up. Their motivation for doing so remains unknown, so their classification is currently unspecified.
 * Trevor Mills ("A Thin Line") - In a last-ditch effort to try and ensure Clark Preston's victory in a mayoral election, Trevor tried to kill opposing candidate Hilary Ross, and likely would have tried to make an attempt on the life of the town's current mayor had he not been killed. His aforementioned motivations classify him as a Type 1 assassin.
 * Izzy Rogers ("Hit" and "Run") - During her former years as a killer, Izzy assassinated at least one politician, an ambassador, and it is presumed she also killed other similar victims. Her motivation for doing so remains unknown, so the classification remains unspecified.

Type 1

 * John Wilkes Booth - Assassinated President Abraham Lincoln.
 * Evan Spencer Ebel - Assassinated Tom Clements, head of the Colorado Department of Corrections.
 * Sirhan Bishara Sirhan - Assassinated New York Senator Robert F. Kennedy.

Type 2

 * Lee Harvey Oswald - Assassinated President John F. Kennedy.
 * James Earl Ray - Assassinated civil rights leader, Dr. Martin Luther King.
 * Arthur Bremer - Attempted to assassinate and, severely wounding the latter.

Type 3

 * Charles Manson - Actress Sharon Tate was one of his victims by proxy.

Type 4

 * Mark David Chapman - Assassinated British musician John Lennon.
 * John Hinckley, Jr. - Assassinated White House Press Secretary James Brady and attempted to assassinate President Ronald Reagan.
 * Robert John Bardo - Assassinated actress Rebecca Schaeffer.