User blog comment:DragonDude83/Is there a term for those who kill to increase their number?/@comment-5653781-20121027015929

they are simply a type of Serial-Killer, like Pinkamena in Cupcakes.. it's really just an Obsession with numbers and should be listed under the existing "Obsession": there may be a scientific term for obsession with numbers but ultimately there is not (nor should there be) a "trope" for killers who kill due to numbers.. they are just serial-killers..

This does not count soldiers or mercenaries who use a "kill tag" type system however (where they mark the number of enemies they've killed) - that is a type of trophy-killing similar to the ancient practice of headhunting etc..