| 100% | ALOU | 4 | Felipe who was the first Dominican-born manager in Major League Baseball |
| 61% | JACOBY | 6 | Ellsbury who was the first Native American of Navajo descent to play in Major League Baseball |
| 48% | MEL | 3 | Allen who was the first host of "This Week in Baseball" |
| 44% | BUCKONEIL | 9 | Negro League great who was the first African-American coach in the MLB and who was inducted into the Baseball Hall of Fame in 2022 (2 wds.) |
| 44% | CHRISTY | 7 | Mathewson who was in the Baseball Hall of Fame's first class |
| 43% | LOUGEHRIG | 9 | His #4 was the first number ever retired by Major League Baseball (Yankees, 1939): 2 wds. |
| 42% | FRANKROBINSON | 13 | Baseball great who became the first African-American manager in the MLB in April 1975 (2 wds.) |
| 42% | HONUSWAGNER | 11 | Pirates shortstop who was inducted in the first Baseball Hall of Fame ceremony in 1939: 2 wds. |
| 42% | LAIKA | 5 | Dog who was the first animal in space |
| 42% | SHEPARD | 7 | Alan who was the first American in space |
| 41% | YURI | 4 | Cosmonaut Gagarin who was the first person in space |
| 41% | ALAN | 4 | Astronaut Shepard who was the first American in space |
| 41% | MAE | 3 | Jemison who was the first Black woman in space |
| 41% | JEMISON | 7 | Mae who was the first Black woman in space |
| 41% | SALLY | 5 | ___ Ride who was the first American woman in space |
| 41% | YURI | 4 | Gagarin who was the first human in outer space |
| 41% | OCHOA | 5 | Astronaut Ellen who was the first Latina in space |
| 41% | THIEL | 5 | Peter who was the first outside investor in Facebook |
| 41% | ELLEN | 5 | Astronaut Ochoa who was the first Latina in space |
| 41% | INDIRA | 6 | Gandhi who was the first female PM in India |
| 41% | RODRIGUEZ | 9 | Yankees player Alex, who was involved in Baseball's first instant replay review, on the day of Halloween |
| 41% | OREE | 4 | Willie who was the first black player in the NHL |
| 41% | YURI | 4 | Cosmonaut Gagarin who was the first human in outer space |
| 41% | RIDE | 4 | Astronaut Sally who was the first American woman in space |
| 41% | MAE | 3 | Astronaut Jemison who was the first Black woman in space |
| 41% | OCHOA | 5 | Astronaut Ellen who was the first Hispanic woman in space |
| 41% | SCAR | 4 | Disney villain who said, "I was first in line . . . until the little hairball was born" |
| 40% | RONALDREAGAN | 12 | U.S. president who was the first born in Illinois, the first to have been divorced, and the first to nominate a woman to the Supreme Court (2 wds.) |
| 40% | STENGEL | 7 | Casey who was the first manager of the New York Mets |
| 40% | GEHRIG | 6 | Yankee who was the first major-leaguer to have his number retired |