Zachary Daniel Weiss (Hebrew: זאק וייס; born June 16, 1992) is an American-Israeli professional baseball pitcher in the St. Louis Cardinals organization.

The Cincinnati Reds added Weiss to their active roster for Opening Day 2018, and he made his major league debut that year.

[5] In October 2018 he became a dual Israeli citizen, partly to help Israel's baseball team make the 2020 Olympics.

[10][5] He was a 2013 Jewish Sports Review Division I College Baseball All-American, along with Alex Bregman and Brad Goldberg.

[24] In 2018 in the minors, between the Arizona Reds, Pensacola Blue Wahoos, and the Louisville Bats he was 3–3 with one save and a 5.40 ERA, and 26 strikeouts in 24+1⁄3 innings.

[25] Reds manager Bryan Price said in spring training in 2018: "if he doesn't make the team I imagine we'll see him at some point during the year.

"[22] Cincinnati added Weiss to their active roster on their Opening Day, March 30, 2018,[1] and he made his major-league debut on April 12, at Great American Ball Park against the St. Louis Cardinals.

[28] During the 2019 season, pitching for the Double-A Pensacola Blue Wahoos and Triple-A Rochester Red Wings, he was a combined 1–3 with a 7.24 ERA in 16 relief appearances, with 30 strikeouts in 27+1⁄3 innings.

[30] On July 19, 2019, Weiss signed with the Long Island Ducks of the Atlantic League of Professional Baseball.

[32] On August 4, 2020, Weiss signed with the Sugar Land Skeeters of the Constellation Energy League.

[29] On February 25, 2021, Weiss signed with the Kansas City Monarchs of the American Association of Professional Baseball.

[34] He began the 2022 season with the Triple-A Salt Lake Bees, with whom he was 2–3 with three saves and a 4.50 ERA in 43 relief appearances, covering 50 innings in which he had 65 strikeouts and held batters to a .226 batting average.

[47] Following his activation from the injured list on July 17, Weiss was removed from the 40–man roster and sent outright to the Triple–A St. Paul Saints.

[48] In 21 appearances split between the rookie-level Florida Complex League Twins, Single-A Fort Myers Mighty Mussels, and St. Paul, he accumulated a 2-1 record and 4.66 ERA with 34 strikeouts.

[50] Weiss pitched for Team Israel at the 2019 European Baseball Championship, going 1–0 with one save and a 0.00 ERA as in four relief appearances he pitched 6+1⁄3 innings and gave up one hit (holding batters to a .050 batting average) and three walks while striking out five batters.

[54] Overall, in three games Weiss pitched seven innings, gave up nine hits and seven earned runs, and struck out 11 batters.

[55][56][57] After the 2023 Hamas-led attack on Israel, Weiss said: "I'm not arguing against the people of Palestine being free and treated fairly, but ... Hamas is a terrorist organization bent on extermination of the Jews and eradicating the world of the land of Israel ... kind of all of our holidays are basically celebrating 'they tried to kill us, and they didn’t get us all.'