William Jennings Buckner (born August 27, 1983) is an American former professional baseball pitcher, who played in Major League Baseball (MLB) for the Kansas City Royals, Arizona Diamondbacks, Los Angeles Angels of Anaheim, and San Diego Padres.

In his fourth season in the Royals organization, Buckner was called up to the big league club on August 24, 2007.

On December 20, 2010, Buckner was signed by the Colorado Rockies to a minor league deal with an invite to spring training.

Buckner had hoped to compete for a spot on the roster, but spent the entire season in Triple-A with the Colorado Springs Sky Sox where he was 4–8 with a 6.03 ERA in 23 appearances.

[4] On May 24, the Padres selected his contract from the Triple-A El Paso Chihuahuas to make a start against the Chicago Cubs that night.

He made 20 appearances (15 starts) split between the Double–A Mobile BayBears and Triple–A Reno Aces, posting an aggregate 5–8 record and 4.00 ERA with 87 strikeouts across 96+2⁄3 innings pitched.