ripper (n.)

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."