Zachary Thomas Duke (born April 19, 1983 in Clifton, Texas) is a starting pitcher in Major League Baseball who currently plays for the Pittsburgh Pirates. Duke bats and throws left-handed.

Duke was drafted directly out of Midway High School in Waco, Texas, in the 20th round of the 2001 draft, and began his career the following year with the Pirates' rookie level Gulf Coast League team. He spent 2003 with the low-A Hickory Crawdads.

In 2004, Duke led all minor league pitchers with a 1.46 earned run average (24 earned runs in 148.1 innings pitched). He posted a 15-6 record in 26 combined starts between Class-A Lynchburg and Double-A Altoona, and his 15 wins tied for third-most among all minor league pitchers.