Loch Ness Monster

The Loch Ness Monster, also known as Nessie, was a fabled creature said to exist in Loch Ness, Scotland.

History
Mr. Burns wanted to find the creature in order to become popular. Burns, along with Homer, Willie and Professor Frink, find Nessie after Frink drains the loch. Mr. Burns and Nessie have a battle off camera and apparently during the fight Nessie swallowed Burns but he still managed to capture the beast, although it is never revealed exactly how he did it. Burns later puts her on display as the 9th Wonder of the World (a la King Kong) and she likes the attention. However, Mr. Burns does not like the flashing camera bulbs and accidentally destroys the stage. She shows affection towards Homer and Mr. Burns before Mr. Burns allows her to work in a casino in Las Vegas.

Non-canon
A tree of evolution reveals that the Loch Ness Monster evolved from snakes and would later evolve into piranhas, which in turn would evolve into.