I have to mention the Loch Ness Monster when talking about games set in Scotland, don’t I?
There have been a few examples in popular culture, ranging from passing mentions to full-on appearances.
Doctor Who explained it via Zygons.
Primeval mentioned it but did an episode about a different legendary lake monster. (I put it in an adventure pitch to Cubicle 7. As well as giving it a guest spot in Hollow Earth Expedition.)
Buffy and Star Trek don’t appear to have had a go at it. Can this be right?