The Wiyot (Wiyot: Wíyot, Chetco-Tolowa: Wee-'at xee-she or Wee-yan' Xee-she', Euchre Creek Tututni: Wii-yat-dv-ne – "Mad River People", Yurok: Weyet) are an indigenous people of California living near Humboldt Bay, California, and a small surrounding area. They are culturally similar to the Yurok people (Wiyot term: Hiktok). They called themselves simply Ku'wil, meaning "the People". Today, there are approximately 450 Wiyot people. They are enrolled in several federally recognized tribes, such as the Wiyot Tribe (also known as the Table Bluff Reservation—Wiyot Tribe), Bear River Band of the Rohnerville Rancheria, Blue Lake Rancheria, and the Cher-Ae Heights Indian Community of the Trinidad Rancheria.

The Wiyot and Yurok are the westernmost people to speak an Algic language. Their languages, Wiyot and Yurok, are distantly related to the Algonquian languages. The Wiyot people's traditional homeland ranged from Mad River (Wiyot name: potawot) through Humboldt Bay (including the present cities of Eureka and Arcata) to the lower Eel River basin. Inland, their territory was heavily forested in ancient redwood. Their stretch of shoreland was mostly sandy, composed of dunes and tidal marsh. They recognized three divisions based on dialect and geography (from north to south):

The Wiyots were among the last indigenous people in California to encounter white settlers. Spanish missions extended only as far north as San Francisco Bay. Russian fur traders in search of sea otter arrived in 1806 but were driven out. During the Gold Rush the Josiah Gregg party came upon Humboldt Bay and skirted the shore. Ships set out to explore northern California's unknown coast. The schooner Laura Virginia located the bay, and in April 1850 made its way in through the dangerous entrance. At the same time pioneers were arriving by land to establish the area's towns. The way of life of the Wiyot people, after many centuries of isolated development, was disrupted by the settlement of Europeans.

Fort Humboldt was established on January 30, 1853, by the Army as a buffer between Native Americans, gold-seekers and settlers under the command of Brevet Lieutenant Colonel Robert C. Buchanan of the U.S. 4th Infantry Regiment. Among the miners, farmers, ranchers and loggers pouring into California, many settled at what is now Eureka. Relationships between the Wiyot and the white colonizers became hostile, marked by raids and vigilante justice.

On February 26, 1860, the Wiyot experienced a massacre which devastated their numbers and has remained a pervasive part of their cultural heritage and identity.

Three days before the massacre, on Washington's birthday, a logging mill engineer from Germany named Robert Gunther bought property on "Indian Island".

The day before the massacre, 25 February, the Weekly Humboldt Times editorialized: "The Indians are still killing stock of the settlers in the back country and will continue to do so until they are driven from that section, or exterminated"; meanwhile prominent local residents had already formed a vigilante committee to deal with the problem, and were sworn to never reveal their membership.

For several days before the massacre, World Renewal ceremonies were being held at the village of Tuluwat, on Indian Island less than a mile offshore from Eureka in Humboldt Bay. Up to 250 Wiyot participated in the ceremonies. The leader of the Humboldt Bay Wiyots was Captain Jim. He organized and led the ceremony to start a new year.