Robert Charles Nieman (January 26, 1927 – March 10, 1985) was an American professional baseball player and scout. An outfielder, he spent all or parts of a dozen Major League Baseball seasons with the St. Louis Browns (1951–52), Detroit Tigers (1953–54), Chicago White Sox (1956), Baltimore Orioles (1956–59), St. Louis Cardinals (1960–61), Cleveland Indians (1961–62) and San Francisco Giants (1962). He also played one season in Japan for the Chunichi Dragons (1963). He threw and batted right-handed, stood 5 feet 11 inches (1.80 m) tall and weighed 195 pounds (88 kg).
Nieman was born in Cincinnati. After attending Kent State University, he was signed by his hometown Reds as an amateur free agent in 1948. He spent three full seasons and part of a fourth in the Cincinnati farm system, although he played only 38 games above the Class A level. In June 1951, he was acquired by the unaffiliated Oklahoma City Indians from the Reds' Tulsa Oilers farm team, and he played 109 games for the 1951 Indians are batted .328. (His combined average, his tenure with Tulsa included, of .324 won him the batting title of the Texas League.)
Nieman then was purchased by the Browns and was added to their active roster in September 1951, setting the stage for his dramatic big league debut. On September 14 of 1951 at Fenway Park, Nieman hit two home runs in his first two major league at-bats. The blows—a solo home run in the second inning and a two-run shot in the third—were hit off Red Sox left-hander Mickey McDermott. Nieman added a single and drove in three runs on the day, but Boston won the game, 9–6. Nieman became the first player in big league history to hit two homers in his first game. Bert Campaneris (1964) and Mark Quinn (1999) are the only others to accomplish the feat. Also, Nieman is one of two players in MLB history to hit HRs in each of his first two big league at bats. Keith McDonald, in 2000, is the other.
Nieman became an everyday outfielder for the Browns, later played regularly for the Tigers and Orioles, and overall he fashioned a 12-year career as a platoon outfielder and pinch hitter. In his 1,113-game career he batted .295, with 125 home runs, 544 RBI, 455 runs, 1,018 hits, 180 doubles, 32 triples and 10 stolen bases. He batted over .300 three times, two of them as a semi-regular player.
In his final MLB campaign, he collected eight pinch hits to help the Giants win the 1962 National League pennant. In the 1962 World Series, and in his only postseason opportunity and last big-league plate appearance, Nieman pinch hit for Ed Bailey in the seventh inning of Game 4 at Yankee Stadium. He drew a base on balls against left-hander Marshall Bridges and was removed for a pinch runner, Ernie Bowman. Bowman would soon score when Giants' second baseman Chuck Hiller hit the first grand slam home run ever struck by a National League player in World Series history. The Giants won that contest, 7–3, but dropped the series in seven games.
After retiring from the field, Nieman served as a scout for over two decades, working for the Indians, Dodgers, Athletics, White Sox and Yankees. He died from a heart attack in Corona, California, at 58 years of age.