William H. Plummer (August 19, 1860 – December 22, 1926) was an American politician in the state of Washington.

[3] He served as prosecuting attorney of Spokane County prior to his election to the state senate.

[3] While serving in the senate, he "fathered the bill that banned gambling in the State of Washington".

[3] He moved to Santa Ana, California around 1920, then returned to Spokane, Washington, and then moved to Los Angeles, California, around 1922, setting up a successful law practice there.

[3] Plummer died in his home in Arcadia, California, at the age of 66, following a month-long illness.