Jeffrey Benjamin Wendelken (/wɛnˈdɛlkɛn/ wen-DEL-ken;[1] born March 24, 1993) is an American professional baseball pitcher in the San Diego Padres organization.

He made his professional debut with the Gulf Coast League Red Sox, posting a 1.27 ERA in 13 appearances.

In 2015, he split the season between the Double-A Birmingham Barons and the Triple-A Charlotte Knights, pitching to a 6–2 record and 3.20 ERA between the two clubs.

[4] On December 9, 2015, Wendelken was traded to the Oakland Athletics, along with Zachary Erwin, for infielder Brett Lawrie.

[9] In 2019, Wendelken was one of four Athletics pitchers to throw 30 innings with a sub 4.00 ERA, joining Liam Hendriks, Yusmeiro Petit, and Ryan Buchter.

[16] He made 61 appearances for Yokohama in 2023, compiling a 2–2 record and 1.66 ERA with 53 strikeouts and 3 saves across 59+2⁄3 innings pitched.