Alfonso Rivas III (born September 13, 1996) is a Mexican-American professional baseball first baseman and outfielder who is a free agent.

He has previously played in Major League Baseball (MLB) for the Chicago Cubs, San Diego Padres, and Pittsburgh Pirates.

Rivas was born on the side of the road along Interstate 805 and raised in Tijuana before moving to Chula Vista, California when he was in the fourth grade.

[7] Rivas signed with Oakland and made his professional debut in 2018 with the Vermont Lake Monsters of the Low-A New York–Penn League, with whom he hit .285 with one home run, 28 RBIs, and 16 doubles over 61 games, winning the team's MVP award.

[17] He made his MLB debut the next day starting at first base against the Chicago White Sox at Wrigley Field, collecting two hits in three at-bats as the Cubs lost 13-1.

[19] On September 21, he was placed on the injured list with a finger injury, thus ending his first MLB season prematurely; over 44 at-bats with the Cubs, Rivas batted .318 with one home run and three RBIs.

[23] On August 1, 2023, Rivas, Estuar Suero, and Jackson Wolf were traded to the Pittsburgh Pirates in exchange for Ji-man Choi and Rich Hill.

[34] Rivas was little league teammates with fellow professional baseball player Javier Assad when the two grew up in Tijuana, Mexico.