Sebastian Castro (born October 14, 2000) is an American professional football safety for the Pittsburgh Steelers of the National Football League (NFL). He played college football for the Iowa Hawkeyes.
Castro attended Harold L. Richards High School in Oak Lawn, Illinois. As a senior, he notched 95 total tackles, with 6.5 tackles for loss, and six interceptions. Castro committed to play college football at the University of Iowa, for the Iowa Hawkeyes.
Castro took a redshirt season in 2019. In the 2021 season, he recorded six tackles in four games. In 2022, Castro notched 33 tackles, a sack, five pass deflections, and a pair of forced fumbles. In week two of the 2023 season, he had four tackles and his first career interception, which he returned 30 yards for a touchdown, as helped the Hawkeyes beat rival Iowa State. For his performance, Castro was named the Big Ten Conference defensive player of the week. In week seven, he tallied seven tackles with two going for a loss, a pass deflection, and the game sealing interception, as he helped Iowa beat Wisconsin. For his start to the season, Castro was named a second-team midseason All-American by the Associated Press.
Castro signed with the Pittsburgh Steelers as an undrafted free agent on April 26, 2025. He was waived on August 26 as part of final roster cuts, and re-signed to the practice squad.
On September 30, 2025, Castro was signed by the Tampa Bay Buccaneers off the Steelers practice squad. He was waived on November 8.
On November 10, 2025, Castro was claimed off waivers by the Steelers.