Kelpies

There are a few different creatures that get called Kelpies in G4.

The first is a unique individual from the comics called Cassie, who has a long serpentine body, tendril-like fins and the ability to control others with her singing. She is later shown as an example of a Kelpie in the My Little Pony Roleplaying Game story "Dark Skies Over Equestria", where they are described as generally peaceful but protective of aquatic creatures. It says they can leave the water for short periods of time but prefer not to.

Creatures called Kelpies but resembling hippocampi are shown in the very next comic issue. Discord says they live in Coltlantis and they are seen in only that one panel and never again.

The Season 10 comics introduce a new species called Kelpies that are much more pony-like. They live in Zecora's homeland of Farasi, have Cutie Marks and can do water- and ice-based magic. They can be on land for longer periods of time but do need water periodically so they don't dry out.