Some Native tribes say that during evolution when the peoples were changing from animal to man, the Seeahtik did not fully absorb the soul power [the tamanaweis] and they became an anomaly in the evolutionary process.

According to the mythology, there are said to be two types of this large, hairy Wildman of the forest. One is a powerful, but benign forest spirit. They are sometimes called Night People and are considered similar to sasquatch. The other is a more fearsome creature; a malevolent man-eater. They are sometimes referred to as Stick Indians.

The two are often mistaken for the other in folklore and tales told by the Native peoples. Each tribe has their name for them and their stories of encounters with them. They are not to be confused with sasquatch. 

Further confusion is caused, however, by the Native belief that it will antagonize the Seeahtik if their names are spoken in public. And so when speaking of them, many natives will use terms like Seatco, which means "spirit". Night People and Stick Indians are used more often.

These creatures were said to be 7 to 8 foot tall with hair covered bodies. Making their homes in caves, they lived high in the mountains of the Olympic Range and deep in seclusion on Vancouver Island. Powers granted them included being able to kill their game by stunning them with hypnotic powers and also being able to instill great fear in men with it; ventriloquism, throwing their voices great distances to confuse those around them; ability to imitate any bird, especially owls; and the ability to make themselves invisible with a medicine that they would rub over their bodies.

Some Natives say that this tribe was kept secret from others as they were so different from the rest. They claim that the Seeahtik are the ones who attacked the prospector's shack in 1924 on Mount St Helens. They were known  to frighten people who displeased them by throwing rocks at them. Tales were also told of how they would come down from the mountains and steal women and babies.

Although they were said to live off the land around their homes, it was said that they would make a yearly pilgrimage to the shores of lakes, rivers or the ocean for a change of diet of fish and other sea foods. They were said to especially love salmon and were not averse to stealing dried salmon from the Natives to take back to their homes.

The Quinalt Indians tell of an incident back in September of 1920. Fred Pope of the Quinalt tribe and George Hyasman of the Satsop tribe were fishing on the Quinalt River. Several of the Seeahtiks came by. The two fishermen had caught a great deal of steelhead trout which the Seeahtiks stole from the canoe.

The Seeahtik could talk with the Clallam Tribe as they spoke the language of the Clallam Tribe. The language was said to have originated from the bear tongue.

Henry Napoleon of the Clallam Tribe is said to be the only Native that was ever invited to a Seeahtik home. Or at least the only Native to return to tell of the event.  It was around 1895 when it occurred.

Henry Napoleon : "I had been visiting relatives near Duncan, B.C. and while there I had been told many stories of the Seeahtiks by the Cowichan Tribe of British Columbia and warned by them not to go too far into the wilderness. However, in following a buck I had wounded I went in farther than I expected. It was at twilight when I came across an animal that I believed to be a big bear but as I aimed at him with my gun he looked and spoke to me in my own tongue. He was about seven feet tall and his body was very hairy. As he invited me to sit down, he told me that I had come upon him unaware and that his mind had been projected to distant relatives of his, otherwise he would never have been seen."

He went on to tell how he was invited to the Seeahtik's home, a large cave on Vancouver Island. While there he was treated with courtesy and told some of their secrets, which included the ventriloquism, bird calls, and invisibility.

Other names that these beings are called include "Mountain Devils", "Gorilla Men", Seatco, Isiatko, Ts'iatkw, See-ah-tik, See-ako, Seeahtkeh, Tsiahk.