William Kavanaugh Oldham (May 20, 1865 – May 6, 1938) was the Acting Governor of the U.S. state of Arkansas for six days in 1913.

He moved to Pettus, Arkansas in Lonoke County in 1885 and became a successful cotton farmer.

When the legislative session ended on March 13, the Arkansas Senate elected Junius Marion Futrell as the new president pro tempore, but Oldham refused to agree that Futrell was the new acting governor; the dispute was settled by the Arkansas Supreme Court on March 24, in favor of Futrell.

He later served as chairman of the state Cotton Reduction Committee.

[5] His younger brother Kie Oldham (1869–1916) served as James Eagle's private secretary while he was governor, curated an important collection of documents about Arkansas' Civil War history, and was a prominent lawyer, working primarily as an advocate for Native American tribes.