ripper (n.) Look up ripper at Dictionary.com
1610s, agent noun from rip (v.). Meaning "killer who mutilates his victims" (1890) is from Jack the Ripper, notorious London murderer, whose nickname contains a pun on ripper in sense of "tool for ripping" old slates, etc. (1823) and the slang meaning "excellent person or thing, a 'ripping' fellow" (1838), from ripping "excellent, splendid."