Proven Victims: 138 Estimated Victims: 400+ Garavito is widely considered to be the most deadly convicted serial killer ever to have lived, earning him the nickname "La Bestia", or "The Beast." He confessed to the killing of 140 children over the course of just half a decade in Columbia, but is suspected of killing and raping at least 400 in total. Are there any other serial killers we should have considered for this list? Do you believe that war criminals or hired killers should qualify? Let us know in the comments below.
