| Mardie Cornejo | |
| Position: | Pitcher |
| Birth Date: | 5 August 1951 |
| Birth Place: | Wellington, Kansas, U.S. |
| Bats: | Right |
| Throws: | Right |
| Debutleague: | MLB |
| Debutdate: | April 8 |
| Debutyear: | 1978 |
| Debutteam: | New York Mets |
| Finalleague: | MLB |
| Finaldate: | September 29 |
| Finalyear: | 1978 |
| Finalteam: | New York Mets |
| Statleague: | MLB |
| Stat1label: | Win–loss record |
| Stat1value: | 4–2 |
| Stat2label: | Earned run average |
| Stat2value: | 2.45 |
| Stat3label: | Strikeouts |
| Stat3value: | 17 |
| Teams: |
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Nieves Mardie Cornejo (born August 5, 1951) is an American former professional baseball relief pitcher who played Major League Baseball (MLB) for the New York Mets. Cornejo played collegiately at the University of Tulsa (TU), and is the father of former MLB pitcher Nate Cornejo, who played for the Detroit Tigers, from to .
Cornejo was first selected by the Washington Senators, in the third round of the amateur draft, and again in the second round of the secondary phase of the 1970 draft, but did not sign. The Mets drafted him in the third round of the secondary phase of the amateur draft, and were also unable to sign him. He eventually signed with the Mets when they drafted him again in the 21st round of the amateur draft.
After five seasons in the Mets' minor league system, he made it to the big league club out of Spring training in . In the second game of the season against the Montreal Expos, Cornejo entered the game in the eighth inning with the Expos leading 5–2, and pitched the final two innings without giving up a run. The Mets, meanwhile, scored two in the eighth and two in the ninth to earn the victory for Cornejo in his Major League debut. Despite respectable numbers (4-2, 2.45 earned run average), Cornejo was back in Tidewater by the end of the season.
Prior to the start of the season, he was traded to the Detroit Tigers for Ed Glynn. After one season with the Tigers' triple-A affiliate, the Evansville Triplets, Cornejo retired from baseball.