Seth Daniel Romero (born April 19, 1996) is an American professional baseball pitcher who is a free agent.

He was not drafted coming out of high school and attended the University of Houston where he played college baseball for the Cougars.

Prior to his sophomore season in 2016, he was suspended indefinitely for "conduct detrimental to the team",[1] described in media reports as poor physical conditioning.

[5] As a junior in April 2017, Romero was suspended by the team for a second time,[6] reportedly after failing a drug test, missing curfew, and being photographed in uniform holding a bong.

[11][7] The Houston Chronicle reported Romero had been involved in a fight with a teammate, precipitating his final dismissal from the team after a series of previous disciplinary incidents.

[13] Romero was assigned to the GCL Nationals, and after one scoreless appearance, was promoted to the Auburn Doubledays where he posted a 5.40 ERA with 32 strikeouts in 20 innings to finish the season.

[18] After placing left-handed reliever Sean Doolittle on the injured list on August 13, 2020, the Nationals selected Romero's contract and promoted him to the major league roster for a game against the New York Mets.

[27] After drafting Romero, the Washington Nationals said publicly they planned to develop him as a starting pitcher rather than pressing him into a relief role.