A gremlin can traverse water. It is humanoid. It is poisonous if eaten.
The gremlin is a highly intelligent and completely evil
creature. It lives to torment other creatures and will go
to great lengths to inflict pain or cause injury.
Suddenly, Wilson thought about war, about the newspaper
stories which recounted the alleged existence of creatures in
the sky who plagued the Allied pilots in their duties. They
called them gremlins, he remembered. Were there, actually,
such beings? Did they, truly, exist up here, never falling,
riding on the wind, apparently of bulk and weight, yet
impervious to gravity?
He was thinking that when the man appeared again.
Nightmare at 20,000 Feet, by Richard Matheson