Mishipeshu.
The Mishipeshu, also known as an underwater panther, is a supernatural marine creature that is well known among the many indigenous peoples of the Northeastern Woodlands and Great Lakes region, particularly among the Anishinaabe.
Mishipeshu are described as water monsters that live in opposition to the Thunderbirds, masters of the powers of the air. Underwater Panthers are seen as an opposing yet complementary force to the Thunderbirds, and they are engaged in eternal conflict.
Mishipeshu was an amalgam of features from many animals: the body of a wild feline, often a cougar or lynx; the horns of deer or bison; upright scales on its back; occasionally feathers; and parts from other animals as well, depending on the particular myth. Mishipeshu are represented with exceptionally long tails, occasionally with serpentine properties. The creatures are thought to roar or hiss in the sounds of storms or rushing rapids.
Mishipeshu were said to live in the deepest parts of lakes and rivers, where they can cause storms. Some traditions believed the underwater panthers to be helpful, protective creatures, but more often they were viewed as malevolent beasts that brought death and misfortune. They often need to be placated for safe passage across a lake.