Hannigan is a surname. Notable people with the surname include:
Alyson Hannigan, American actress
Barbara Hannigan, Canadian soprano
Ed Hannigan, American comic book writer and artist
James Hannigan, British composer
Lisa Hannigan, Irish singer and songwriter
Robert Hannigan, senior British civil servant and author of a report informally known as the Hannigan Report
Fictional characters:
Miss Agatha Hannigan, fictional character in Annie