Frankenstein's monster

Short definition from Wiktionary

Proper noun

1. 1
   Frankenstein's monster, the creature from Mary Shelley's 1818 novel

Noun

1. 1
   A thing that is cobbled together from parts of other things.
2. 2
   A creation that overpowers or slips out of the control of its creator, often proceeding to turn on its creator or harm others.