Which pitcher gave up Jackie Robinson's first Major League home run?

Dave Koslo gave up Jackie Robinson’s first Major League home run. Robinson hit the milestone on April 18, 1947, against Koslo of the New York Giants at the Polo Grounds in New York City.

The home run came in the third inning of Robinson’s fifth Major League game. He drove the ball over the left-field wall, helping the Brooklyn Dodgers defeat the Giants 9–7. Robinson had already made history five days earlier by becoming the first Black player to appear in a modern Major League game, but the home run added an immediate sporting milestone to his groundbreaking season.

Koslo was a left-handed pitcher who spent most of his career with the Giants and later played for the Baltimore Orioles and Milwaukee Braves. He led the National League in earned-run average in 1949 and later won the opening game of the 1951 World Series. Robinson finished his rookie season with 12 home runs and was named the first-ever Rookie of the Year in the modern award’s inaugural year.