It's a Mad Mad Mad Mad World

• Edie Adams as Monica Crump, wife of Melville Crump
• Milton Berle as edible seaweed company owner J. Russell Finch
• Sid Caesar as dentist Melville Crump (a role originally meant for Ernie Kovacs before his death in a car accident)
• Buddy Hackett as gambler Benjy Benjamin
• Ethel Merman as Mrs. Marcus, mother-in-law of J. Russell Finch and a very cranky woman
• Dorothy Provine as Emeline Marcus-Finch, wife of J. Russell Finch
• Mickey Rooney as gambler Dingy 'Ding' Bell
• Dick Shawn as Sylvester Marcus, Mrs. Marcus' son and Emeline's brother
• Phil Silvers as Otto Meyer
• Terry-Thomas as Lt. Col. J. Algernon Hawthorne
• Spencer Tracy as Captain C.G. Culpepper
• Jonathan Winters as truck driver Lennie Pike

Secondary characters:

• Eddie 'Rochester' Anderson as a cab driver
• William Demarest as Santa Rosita's chief of police (Aloysius)
• Jimmy Durante as Smiler Grogan
• Peter Falk as a cab driver
• Paul Ford as Col. Wilberforce

Cameo appearances by:

• Jim Backus as boozy airplane owner Tyler Fitzgerald
• Jack Benny as a man who drives by in a Maxwell, offering to help
• Paul Birch as a policeman
• Ben Blue as the biplane pilot
• Joe E. Brown as the union official
• Alan Carney as a police sergeant
• Chick Chandler as detective outside of Chinese laundry
• Barrie Chase as Sylvester's love interest
• John Clarke as helicopter pilot
• Stanley Clements as squad room detective
• Lloyd Corrigan as the mayor of Santa Rosita
• Howard Da Silva as airport official
• Andy Devine as the sheriff
• Selma Diamond (voice only) as Ginger Culpepper
• Minta Durfee
• Roy Engel as patrolman
• Norman Fell as a detective
• James Flavin as patrolman
• Stan Freberg as a deputy sheriff
• Nicholas Georgiade as detective
• Louise Glenn (voice only) as Billie Sue Culpepper
• Leo Gorcey as a cab driver
• Don C. Harvey as policeman
• Sterling Holloway as the fire chief
• Edward Everett Horton as Mr. Dinckler
• Allen Jenkins as police officer
• Marvin Kaplan as garage man Irwin
• Robert Karnes as Officer Simmy
• Buster Keaton as Jimmy the Crook (boatman)
• Tom Kennedy as the traffic cop
• Don Knotts as the nervous motorist
• Charles Lane as the airport manager
• Harry Lauter as police dispatcher
• Ben Lessy as George the steward
• Bobo Lewis as pilot's wife
• Jerry Lewis as the man who runs over Culpepper's hat
• Mike Mazurki as the miner bringing medicine to his wife
• Charles McGraw as Lt. Matthews
• Cliff Norton as a reporter
• Barbara Pepper
• ZaSu Pitts as the switchboard operator
• Carl Reiner as the tower controller
• Madlyn Rhue as Secretary Schwartz
• Roy Roberts as a policeman
• Eddie Ryder as air traffic control tower staffer
• Arnold Stang as garage man Ray
• Nick Stewart as migrant truck driver
• The Three Stooges appear for about five seconds as firemen in the airport scene. There is no dialogue and they do not move. Apparently, it was felt that the mere sight of their very familiar faces in the guise of protectors of life and limb was sufficient to convey the humor. Kramer and the producers were right, as audiences reportedly howled with laughter at every showing when the Stooges cameo appeared.
• Sammee Tong as a laundryman
• Doodles Weaver as a hardware store employee
• Jesse White as an air traffic controller

Wikipedia