The Multnomah are a tribe of Chinookan people who live in the area of Portland, Oregon, in the United States. Multnomah villages were located throughout the Portland basin and on both sides of the Columbia River. The Multnomah speak a dialect of the Upper Chinookan language in the Oregon Penutian family.

The Multnomah people are a band of the Chinookan peoples who originally resided on and near Sauvie Island in Oregon. The Multnomah and the related Clackamas tribes lived in a series of villages along the river near the mouth of the Willamette River on the Columbia River (the Willamette was also called the "Multnomah" in the early 19th century). According to archaeologists, the villages in the area were home to approximately 3,400 people year-round, and as many as 8,000 during fishing and wappato-harvesting seasons (wappato is a marsh-grown plant like a potato or onion and a staple food).

In 1830, a disease generally thought to have been malaria devastated the Multnomah villages. Within five years, the village of Cathlapotle was abandoned and was briefly inhabited by the Cowlitz tribe. The Multnomah people had nearly been wiped out by the year 1834 due to malaria and smallpox outbreaks. With only a few Multnomah left by the year 1910, the remaining people were transferred to the Grand Ronde Community which is also located in the Northwest of Oregon.

In 1854 Multnomah County became an official part of Oregon. The Multnomah people were located in today's Multnomah County, but more specifically, they inhabited Sauvie Island on the Columbia River. The Native American term for Sauvie Island was Wappatoo Island. The Multnomah people shared Sauvie Island with other Chinook tribes under the collective name The Cathlascans. Furthermore, the Multnomah people were considered “upper Chinook” and spoke the Wasco-wishram language.

One of the larger villages, Cathlapotle, was located in present-day Clark County, Washington at the confluence of the Lewis River with the Columbia River and was visited by the Lewis and Clark Expedition in 1805. According to their journals, Lewis and Clark found 14 houses in the village, most of them ranging from 14-by-20 ft (4.3 m by 6.0 m) to about 40-by-100 ft (12 m by 30 m). They reported that approximately 900 people lived in the villages. The Cathlacomatup were a group of Multnomah that resided along the Multnomah Channel at the Wappatoo Inlet. Lewis and Clark came into contact with the Cathalacomatup in 1805.

The existence of the great chief named Multnomah has been up for debate. Other Native American tribes in the Columbia River Valley area spoke of him in their oral history, while Oregon historians dismissed him as just a myth. Therefore, there is conflicting evidence of whether or not he was real. The Oregon Historical Society had multiple presidents throughout the 1900s who dismissed him as only an imagined chief. However, on top of the oral descriptions of him there were writings including newspapers and journals, which indicate he was indeed real.

Multnomah was the chief of tribes ranging across much of the Pacific Northwest from Oregon to Canada, and, during his 40 years of power, he was chief of the Willamettes, as well as war chief of the tribes and communities of Wauna, Oregon, ruling from his station on what is known today as Sauvie Island.

Ann Fulton, a history professor at Portland State University, found and collected much of what is known of Chief Multnomah from many written stories. She documented this in her paper The Restoration of an Iłkák'mana: A Chief Called Multnomah. She hoped to bring more awareness to his existence. Particular accounts came from people such as William Tappan and Dr. Elijah White, both agents of Indian tribes. The many verbal and written accounts of Chief Multnomah were similar. He was regarded highly, and many stated that while he was a warrior chief, he was very respected among his people.