The stories were situated in Good Haven, a fictitious city that was continually beset by various supervillains. When trouble occurred, the city launched a massive fireworks display to summon a quintet of high-flying superheroes into action.
The team members were clumsy accident-prone bunglers who often found themselves in silly situations. A typical occurrence had them hopelessly tangled together offering each other stock apologies, often while falling en masse into an even worse situation. In combat, they were even worse, continually getting into each other's way until they were all captured by the villain (who almost always had enormous V-shaped teeth). However, having escaped the villain's death trap in the cliffhanger, the team always managed to regroup and fight with proper coordination to win the day. In an episode of Mighty Mouse: The New Adventures, which Bakshi also produced, the Mighty Heroes had retired and become accountants with a firm called "Man, Man, Man, Man & Man."
The series came about when the Terrytoons staff were pitching series proposals to the animation company's parent corporation, the CBS television network, only to have them all rejected. When the CBS representatives asked if there were any other proposals, Bakshi, at the time a former "boy wonder" animator who had been recently promoted to director and invited to the meeting, spoke up and improvised the proposed The Mighty Heroes on the spot.
The cartoons originally appeared as a segment of the long-running Mighty Mouse Playhouse during the 1966-67 season, which was renamed "Mighty Mouse and The Mighty Heroes" in recognition of the new segment. Some weeks during the network run, two complete "Mighty Heroes" segments would open and close the show with a classic Mighty Mouse cartoon in-between. In other weeks, one Mighty Heroes episode would be split in two to open and close the show, with two Mighty Mouse cartoons broadcast in-between.
The character voices were provided by Herschel Bernardi, who provided those of Strong Man, Diaper Man, and Tornado Man, and Lionel G. Wilson, who provided those of Cuckoo Man and Rope Man. Bernardi was also the original provider of the "Ho Ho Ho" voice of the Jolly Green Giant and of StarKist's Charlie the Tuna voice in commercials. Wilson was also the voice of the title character in another famous Terrytoons series, Tom Terrific. Only 20 episodes were produced; the series came to an end when Bakshi left Terrytoons in 1967.
Reruns of The Mighty Heroes were eventually syndicated by Viacom (now CBS Television Distribution) in the 1970s as part of the Mighty Mouse package. There have also been licensed VHS releases of some episodes and bootleg DVD releases of the entire series, but there has never been an authorized DVD release of the show. Episodes of The Mighty Heroes also appeared in movie theatres for a time, with an episode shown to audiences, preceding the main attraction.
Their last appearance in animated form was as guest stars in the episode "Heroes and Zeroes" of the late 1980s series Mighty Mouse: The New Adventures, produced by Bakshi, in which they had all retired and were running the accounting firm of Man, Man, Man, Man and Man. Even Diaper Man had grown up, evidenced by his wearing a moustache.
The individual Mighty Heroes
All five of the Mighty Heroes had the power to fly. Individually, they were these:
- Strong Man is the "Superman" of the group, who has incredible strength—if not invulnerability. He speaks with a friendly southern farm-boy type accent, somewhat similar to Jim Nabors's Gomer Pyle voice, and holds a civilian job as a mechanic. His favorite fighting move is his "Jet-propelled blow" where he flies into a villain fist-first.
- Rope Man is a sailor who works at the Docks. A very erudite fellow with a light British accent, Rope Man's body is a seemingly unending length of rope. He can use his hands like lassos, and can even weave himself into a net. The drawbacks to his powers are that he often gets tangled up or knotted, not rarely around his own teammates. He also tends to talk too much.
- Tornado Man is a television weather-man who can spin himself into a tornado. He often sucks the villains into his vortex then shoots them out towards the nearest solid wall. He speaks in a wheezy voice.
- Cuckoo Man is a bird shop owner whose powers are simply bird-based. Unlike the other heroes, who can fly with no effort, Cuckoo Man has to flap his arms almost constantly in order to keep aloft. Cuckoo Man changes into his costume by jumping up through the bottom of his store's cuckoo clock and popping out through the little door. He may be the least effectual of the heroes, but he is not useless. While the other heroes's flying is accompanied by a "jet" sound effect similar to Mighty Mouse's, Cuckoo Man's is represented by a chugging jalopy engine sound much like Jack Benny's Maxwell automobile.
- Diaper Man, whose primary alias is pronounced by the announcer as "...and Di-ah-per Man," is a red-headed, diapered, yet fully articulate baby as well as the leader/brains of the group, who sounds a lot like Popeye the Sailor. His main weapon is his bottle, which by holding on to the rubber nipple, he can swing (or shoot like a slingshot) around forcefully. The bottle can also shoot high pressure streams of baby formula. In emergencies, Diaper Man (and often Strong Man) will drink some formula from the bottle when extra strength is needed.
Almost all of the 20 episodes were named after the enemies the Mighty Heroes encountered in each.
- The Plastic Blaster
- The Frog
- The Junker
- The Shrinker
- The Ghost Monster
- The Stretcher
- The Monsterizer
- The Drifter
- The Shocker
- The Enlarger
- The Toy Man
- The Dusters
- The Big Freeze
- The Timekeeper
- The Scarecrow
- The Time Eraser
- The Return Of The Monsterizer
- The Paper Monster
- The Raven
- The Bigger Digger
Although some sources list The Proton Pulsator as a 21st episode, this was actually an episode of The Astronut Show.
The series had no opening/closing titles of its own.