Eel

 While the electric and giant moray eels share a basic form, and an ability to slowly move on land, these are otherwise quite different critters.

The annual dwarven Highland games include many, many feats of strength and endurance. One of them is a race through a knee-high muddy pond crawling with electric eels. While serious injuries are rare, folks falling face-down and rolling over each other in the mud are expected, and treated with jest.
The winner traditionally gets a thunder-infused weapon, as well as a hearty eel soup.

A sea hag who often bargains with pirates resides in a cave accessible only by diving beneath the waves. While the cavern is by no means hard to reach, especially during low tide, a moray eel decided to lair at it's very mouth. What should have been a simple dive now becomes a deadly encounter, especially for those who come unprepared and are ambushed by the dread creature.

Junkeep is the capital of a newly formed goblin kingdom. The stinky keep, built out of incredible amounts of scrap material, is also surrounded by a moat that also serves as a sewer. In that filth-ridden liquid resides the royal alchemist's greatest achievement - a huge moray eel that also has the electricity-producing glands of its smaller cousins. While it has an aversion to goblin meat, the creature has been known to crawl out of the water and attack the city's few guests on occasion.