| Károly Peyer | |
| Order: | Minister of the Interior of Hungary |
| Term Start: | 1 August 1919 |
| Term End: | 7 August 1919 |
| Predecessor: | Jenő Landler and Béla Vágó |
| Successor: | Adolf Samassa |
| Birth Date: | 9 May 1881 |
| Birth Place: | Városlőd, Hungary |
| Death Place: | New York City, United States |
| Profession: | politician |
| Party: | MSZDP |
Károly Peyer (9 May 1881 – 25 October 1956) was a Hungarian politician who served as Interior Minister for six days after the end of the Hungarian Soviet Republic in 1919. He was later Minister of Works in the cabinets of István Friedrich and Károly Huszár. He took part in the consolidation policy of István Bethlen in 1921: as the leader of the main opposition party (the Hungarian Social Democratic Party) he compromised with the Prime Minister (the Bethlen-Peyer Pact). Peyer was called "betrayer of the left-wing" by the communists.
In 1947 Peyer was excluded from his party, so he joined to the Hungarian Radical Party, which organised against communist rule. Soon Peyer emigrated to the United States. The next year the People's Tribunal sentenced him to 8 years.
Peyer died of a heart attack on 25 October 1956, while listening to the news of the Hungarian Revolution of 1956, which broke out two days earlier.