Cahalan is an Anglicized Irish surname derived from the given name Cathalán. Notable people with the surname include:
Adrienne Cahalan (born 1964), Australian sailor Cissie Cahalan (1876–1948), Irish suffragette Robert Cahalan (born 1946), American atmospheric scientist Sinéad Cahalan, Irish camogie player Susannah Cahalan (born 1985), American journalist and author Vera Cahalan Bushfield (1889–1976), American politician
See also Cahalane, surname Cahillane, a surname