César Miguel Valdez (born March 17, 1985) is a Dominican professional baseball pitcher for the Leones de Yucatán of the Mexican League.

He has previously played in Major League Baseball (MLB) for the Arizona Diamondbacks, Oakland Athletics, Toronto Blue Jays, Baltimore Orioles, and Los Angeles Angels, and in the Chinese Professional Baseball League (CPBL) for the Lamigo Monkeys.

The following year, Valdez split the season between the High-A Visalia Oaks and the Double-A Mobile BayBears, accumulating a 13–8 record and 3.14 ERA with 140 strikeouts in 160.1 innings of work.

For the 2009 season, Valdez played for the Triple-A Reno Aces, registering a 7–6 record and 4.78 ERA in 19 appearances.

[2] Valdez was promoted to the major leagues for the first time on May 3, 2010, and made his MLB debut later that day, pitching 5.0 innings of 1-run ball against the Houston Astros.

On January 1, 2016, Valdez signed a minor league contract with the Houston Astros organization and was invited to spring training.

[1] He spent the entire 2016 season with the Triple-A Fresno Grizzlies, and posted a 12–1 record, 3.12 ERA, and 114 strikeouts in 1381⁄3 innings.

[13] In July, Valdez was recalled by the Blue Jays and added to the starting rotation after Aaron Sanchez was placed on the disabled list.

In 2019, he pitched to a 15–2 record with a 2.26 ERA and 122 strikeouts across 147.2 innings, winning the league's pitcher of the year award and being named an All-Star.

[20] On January 4, 2020, Valdez requested and was granted his release in order to pursue an opportunity with an MLB-affiliated organization.

[23] He pitched three scoreless innings in relief in his first MLB appearance in three seasons in a 5–0 loss to the Blue Jays at Sahlen Field two nights later on August 29.

[24] He earned his first MLB save with two shutout innings in a 6–3 win over the New York Yankees in the nightcap of a twi-night doubleheader at Camden Yards on September 4.

[33] He allowed two runs on two hits while failing to strike out a batter against the Texas Rangers and was designated for assignment the next day.

On December 3, Valdez re–signed with the Angels on a minor league contract that included an invite to spring training.

[35] Valdez began the 2023 season with Triple-A Salt Lake, making 7 appearances (4 starts) and posting a 7.27 ERA with 25 strikeouts in 26.0 innings pitched.

[41] He primarily throws a changeup which he uses 81.3% of the time, tops out at 82 miles per hour and drops 8.5 inches more than the average for that type of pitch according to Statcast.