Satchel Paige: Signed with Cleveland in 1948 after a legendary career in the Negro Leagues at the presumed age of 42. He became the first Negro pitcher in the majors and helped lead Cleveland to the World Series title. He later pitched for St Louis Browns from 1951-53, making two All-Star games.
Willard Brown: Signed with St Louis Browns in 1947 along with Hank Thompson. Brown is considered widely as one the best home run hitters in Negro League history. Josh Gibson gave him the nickname, "Home Run" Brown. When Brown and Thompson debuted with the Browns, it was the first time black players played together in the majors. Brown was also the first black player to hit a home run in American League history. But after becoming frustrated with racial slurs and playing on a poor team, he returned to the Negro Leagues after just a month in the majors.
Hank Thompson: Debuted with Willard Brown for St Louis in 1947. He also played only briefly with the Browns. He did, however, sign with New York Giants in 1949 along with Monte Irvin. By becoming a Giant, Thompson was the first player to integrate two different franchises and also the first black player to play in both the American and National Leagues. Couple of other firsts he is credited for is when he faced Brooklyn's Don Newcombe, it was the first time a black hitter faced a black pitcher in MLB history and in 1951, along with Irvin and Willie Mays, they became the first all black outfield.
Don Newcombe: Debuted with Brooklyn Dodgers in 1949. Had a successful career with Dodgers which included Rookie of the Year, MVP and Cy Young awards. He along with Doby, Robinson and Roy Campanella were the first black All-Stars in 1949. Also in 1949, he was the first black player to start a World Series game.
Roy Campanella. Debuted with Brooklyn in 1948. Had a Hall of Fame career which included eight All-Star game appearances, three National League MVPs and a World Series championship. Unfortunately, his career ended after being paralyzed in a car accident during the 1958 season.
Joe Black: Also played for Brooklyn and debuted in 1952. Black was the NL Rookie of the Year and during the 1952 World Series, became the first black player to win a World Series game. He later played for Cincinnati and Washington before retiring 1957.
Sam "The Jet" Jethroe: After seeing Jackie Robinson success with Brooklyn, Branch Rickey signed Jethroe to play for the Brooklyn's minor league club, Montreal Royals in 1948. Didnt make his Major League debut until 1950 when he was traded to the Boston Braves. At the age of 32, Jethroe won the NL Rookie of the Year
Minnie Minoso: Debuted with Cleveland in 1949 and later starred with Chicago White Sox. He played on nine All-Star teams and won three Gold Gloves.
Luke Easter: Played with Cleveland from 1949-54, he was known for his power. His home runs were known as "Easter Eggs". Unfortunately he battled knee injuries throughout his career and never realizing a full career.
There is a few of the pioneers who blazed the trail for future black players in the Major Leagues. Each of these players made an impact on the game in some way. And here is a trailer for the movie, 42, that will be released in April : http://www.youtube.com/watch?v=I9RHqdZDCF0