Xenophon Pierce Wilfley (/ˈzɛnəfɒn ˈwɪlfli/; March 18, 1871 – May 4, 1931) was a Democratic Party politician who represented the state of Missouri in the U.S. Senate for five months in 1918.

In 1918 Wilfley was appointed to the United States Senate by Governor Frederick D. Gardner as a Democrat to fill out the term of William J.

Wilfley served from April 30 to November 5 and was the chairman of the Committee on Industrial Expositions.

After leaving the Senate, Wilfley returned to St. Louis and resumed his legal practice, becoming president of the Missouri Bar Association in 1925.

He died in St. Louis in 1931 at the age of 60 and is buried in Oak Grove Cemetery.