John Cassidy
John Cassidy may refer to:
- John Cassidy (artist), Irish sculptor and painter
- John Cassidy (baseball), American baseball player
- John Cassidy (basketball), Canadian Olympic basketball player
- John Cassidy (journalist), business journalist and published author
- John Cassidy (magician), American magician and balloon artist
- John Cassidy (author), American author and publishing executive
- John Cassidy (chancellor), Australian businessman and former university chancellor
- John Cassidy (seismologist), Canadian seismologist
- John Cassidy (speed skater), Canadian Olympic speed skater
- Jack Cassidy, American actor
- John Edward Cassidy, American lawyer; Illinois Attorney General
- John E. Cassidy Jr, member of the Illinois House of Representatives.
- John F. Cassidy, Vice Chairman of the board and former Chief Executive Officer of Cincinnati Bell Inc.
- John Joe Cassidy, Gaelic football player for Cavan
- John P. Cassidy, Los Angeles City Council member, 1962–1967