| Fred Demarais | |
| Position: | Pitcher |
| Bats: | Unknown |
| Throws: | Right |
| Birth Date: | November 1, 1866 |
| Birth Place: | Montreal, Quebec |
| Death Place: | Stamford, Connecticut |
| Debutleague: | MLB |
| Debutdate: | July 26 |
| Debutyear: | 1890 |
| Debutteam: | Chicago Colts |
| Finalleague: | MLB |
| Finaldate: | July 26 |
| Finalyear: | 1890 |
| Finalteam: | Chicago Colts |
| Statleague: | MLB |
| Stat1label: | Win–loss record |
| Stat1value: | 0-0 |
| Stat3label: | Strikeouts |
| Stat3value: | 1 |
| Stat2label: | Earned run average |
| Stat2value: | 0.00 |
| Teams: |
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Frederick Demarais (November 1, 1866 – March 6, 1919) was a pitcher in Major League Baseball with the Chicago Colts of the National League. He pitched two scoreless innings for the Colts on July 26, 1890, in his only major league appearance. His minor league career lasted through 1894.