Randy, the Guinea Pig that broke into the female enclosure at his Zoo, and impregnated around 100 females in 2014. He then became a father of around 400 babies.
https://www.itv.com/news/2014-06-06/guinea-pig-to-become-father-to-400-after-breaking-into-female-enclosure/

Original tweet : https://twitter.com/tilbots/status/1236211468980441088