"Nessie" is the nickname given to the mythical beast that allegedly lives in Loch Ness / Scotland. It appears in two of the classic Wizardry games as a mighty opponent.
Nessie in Wizardry V Edit
The beast can be found at the very bottom of the pool in Level 4. After paying 2500 GP to the pool's guardian, a woman with a whip, a character has to descend all the way to level 10. Nessie is accompanied by "Loch Babies", which might be her offspring.
After winning the fight, the characters find the Skeleton Key.
Nessie in Wizardry 8 Edit
She is by far the largest monster in the whole game. She can be found underwater in a large area in the Bayjin Shallows. It is not necessary to kill the monster, as the party can sneak by. However, killing Nessie will give the party a lot of experience points, as well as being able to get to Davy Jones' Locker, which has a chance of spawning powerful, rare items, like Excalibur.