Deletion of List of worst mass murderers and spree killers

Comment: as redundant to the nom's provided articles. Also "worst" is too vague. I can't find sources that describes a Top 20 list and Top 25 list for the mass killings and disgruntled employees part in Google Books, Google and Google Scholar so it is safe to assume that this is |Original research
Stance: delete
Cited policy: Wikipedia:No original research (WP:OR)