From Wikipedia:

William Alexander Aitken was a fur trader with the Ojibwe.

Aitken was noted as a native of Edinburgh, Scotland. He came to the Upper Mississippi region around 1802 {said to be 15y old at the time} from Canada and was employed by John Drew, a trader in the Mackinac area. Aitken worked as a clerk in John Jacob Astor's American Fur Company; he was assigned to William Morrison's Fond du Lac Department.

In 1831, Aitken became the Department's chief trader, establishing his headquarters at Sandy Lake, Minnesota. He had trading posts in the Fond du Lac District, which went as far to the west as Pembina, North Dakota, to the north as Rainy Lake and to the south below the mouth of the Crow Wing River. In 1836 he had a major disagreement with Ramsay Crooks, and in 1838 he was discharged for mismanagement.

Aitken set himself up in competition as an independent trader on the Upper Mississippi out of St. Louis, Missouri. He died September 16, 1851. He was buried on the east bank of the Mississippi opposite to the mouth of the Swan River in Morrison County, Minnesota, where he had a trading post from 1842 until his death. Died at Sandy Lake in 1851.
Sandy Lake is an unincorporated community Native American village located in Turner Township, Aitkin County, Minnesota, United States

Aitken had at least six wives:
1 Mary Hole-in-the-Day (Ombebewonoquay), daughter of Chequodaince/Kechequodaince/Quodaince and Kechekahdayquayz/Chekahdahquayzai;
2 Gin-gion-cumig-oke;
3 Madeline Ermatinger b.1808 Red River Settlement (Beshakwadokwe, Striped-Cloud; recorded variously as Payshahquodoquay, Pach-a-kwa-dok-we, etc.) d/o Charles Oakes Ermatinger (1776-1853) & Charlotte Kalawabide (Kattawabide/Cattoonalute/Manacowe) who died 1880.
birth (III)-Madeleine (Striped Cloud) Ermatinger Metis daughter (II)- She married William A. Aitken.
4 Nu-gu-nay-au-nah-quod;
5 Odishkwaagamiikwe (End-of-the-Lake Woman; recorded as O-dish-quah-gah-me-qu[ay]); and
6 Julia Quodaince.

He was said to have had 25 children among his wives, including a daughter Mathilda Aitken, who married William Whipple Warren #175623521. One of the first criminal trials in Minnesota Territory concerned the murder of his son Alfred. George Bonga was involved in the hunt of his killer Che-ga-wa-skung

Aitkin County, Minnesota and the city of Aitkin, Minnesota are named after him

Sandy Lake, Minnesota
Gaa-mitaawangaagamaag
46.799306, -93.250972
45.9223022,-94.3792191 mouth of Swan Lake
http://www.rootsweb.ancestry.com/~mnrrvn/Metis-1805-1808.html
(I)-William Alexander Aitken (Aitkin) aka Aitki of Edinbugh, Scotland died September 16, 1851 Swan River Post (Aitkinville) arrived in the Great Lakes region being employed by John Drew about this time. It is said he had at least two wives (III)-Striped Cloud Madeline Ermatinger Metis Payshahquodoguay daughter of (II)-Charles Oakes Ermatinger (1776-1853) and Charlotte Kalawabide (Kadowaubeda) and Gingioncumigoke. He is said to have 25 Metis children some named Alfred murdered at Red Ceder Lake about 1836, John, Matilda, Roger, Nancy, Elizabeth, Ann, Julie E., Salina, Robert, Amanda, Sarah J., Childe, Isabel, Henry and Edgar. William later worked for the American Fur Company in William Morrison'e Fond du Lac Department. Later he was chief trader at Sandy Lake operating into Pembina to the west and Rainy Lake to the north and south to the Crow Wing River.
Red River (II)-Charles Oakes Ermatinger (1776-1853), wife Charlotte Kalawabide (Kattawabide/Cattoonalute/Manacowe) who died 1880 and family are transferred from Sault Ste Marie to Red River of the north (Lake Winnipeg) working for William McKay of the North West Company. He married their daughter.