William Plankinton (November 7, 1843 – April 29, 1905) was an American businessman, manufacturer, and industrialist.

Plankinton was associated with the Milwaukee museum, public library, industrial exposition and Chamber of Commerce.

[3] The firm became known in 1893 as the Plankinton Packing Company when the Cudahy brothers moved their operations south to a site just outside of Milwaukee.

[7] He founded and was part owner of the Western Portland Cement company in Yankton, South Dakota.

[11][12][13] The bank crisis involved a scandal of fraud and embezzlement in which Plankinton was implicated.

[15][16][17] Loans made by the bank to Frank A. Lappen and his companies totaling almost $300,000 precipitated the crisis.

[18][19][20] Lappen was summoned to court to testify about his failure to pay back creditors $750,000, but disappeared to Mexico and could not be extradited.