ALL KINDS OF KILLERS

Your story has a killer.  Your hero must stop him.  But is your villain a serial killer, a spree killer, or a mass murderer?  Or none of the above.  You must know the difference to understand how to characterize your antagonist.

A serial killer has killed multiple times but always at a different location over a period of time. There is usually a pattern as to location, type of victim, method of murder, etc. with the victim almost always previously unknown to the killer.  The Ted Bundys and John Wayne Gacys fit in this category.

Ted Bundy

A spree killer has killed multiple times at different locations but the murders are considered one continuing event (more or less a crime wave). An example would be Bonnie Parker & Clyde Barrow and gang who killed about a dozen in the course of committing robberies and killing police officers.

Bonnie Parker & Clyde Barrow 

A mass murderer kills many people in a single event.  The Aurora, CO movie theater shooting and the Newtown school shooting are examples.

Each type of killer possesses different motivations and displays certain characteristics. Not all killers are multiple murderers.  They may strike once and have no intention or incentive to kill again such as domestic homicides, revenge killers, arsonists, and others.