In the same episode, other parallel universes are visited, including a universe where everyone lack eyes, where their heads are bobble-heads, where everybody is a robot, a Roman Empire themed universe (complete with Roman numerals calculus) and a Hippie universe... However there do seem to be universes without the main characters, such as an octopus universe, a universe filled only with women and a completely frozen universe.
In "All The President's Heads", the gang travels back in time to The American Revolution to stop Prof. Farnsworth's ancestor David, who betrayed the Revolutionaries by counterfeiting money. After they stop David, Fry burns the counterfeit bills with a lantern he found in a church, which turned out to be one of the lamps used to signal the coming of the British (one if by land, two if by sea). Because of this, the British win the war and the gang come back to an America that's still under British rule.
In "The Devil's Hands Are Idle Playthings", Robot Devil sets up a "ridiculously circuitous plan" that bounces from Bender, Calculon, Leela, and Fry's opera which ends with either him marrying Leela or getting his robot hands back from Fry.
Most of Timmy's time traveling adventures in The Fairly OddParents backfire because he doesn't realize until it's too late that he was the nail that made things go wrong; for instance, a Stable Time Loop involving Mr. Crocker's obsession with fairies.
Averted. Cosmo was the one who originally caused Crocker to become the way he was. Timmy just inadvertently caused it again except things also played out so Crocker now has better Fairy Hunting tech.
Not to mention the episode where he wishes he was never born. Tuns out his gender is a nail as well - his parents had a girl instead, and the life of everyone Timmy knows is better for it.
There was also the episode "Father Time" where Timmy, after melting his dad's trophy with Heat Vision, goes with Cosmo's crazy idea to go back and time to stop his father from winning the stupid trophy in the first place. When that happened, Timmy's dad gets the last place prize; an all expense paid scholarship to Dictator School, where he rules Dimmsdale in a dark future with creepy happiness and never got to marry Timmy's mom. So Timmy doesn't exist and lost his godparents (who vanish JUST before the revelation of Dictator School).
On the fifth season finale of Family Guy, Peter goes back in time to sow his wild oats and ends up not marrying Lois, who married Quagmire instead. Apparently, their not marrying allowed Al Gore to become President — and Gore apparently killed Bin Laden, instituted zero-tolerance gun control and universal health care, and fixed the public school system. In addition to all that, Dick Cheney shot Tucker Carlson, Antonin Scalia, and Karl Rove. With one bullet. Brian likes it this way. Whew. Even after they "fix" the time-stream, the present still isn't the same: somehow, Roger the Alien ended up in their house.
Done in a Christmas episode of American Dad!. Stan was sent back to 1970 to renew his Christmas spirit, and uses the opportunity to kill Jane Fonda, whom he blames for modern day liberalism. Though instead of killing her, Stan somehow convinces Martin Scorsese to quit drugs and thus Taxi Driver was never made; as a result, John Hinkley, Jr. never got obsessed with Jodie Foster, and never tried to assassinate Ronald Reagan to impress her. Reagan loses the election to Mondale, who immediately handed America over to the Soviets. The timeline is fixed by the end of the episode (Stan shoots President Reagan), except for Roger who became the inventor of disco, because he found a Best of Disco cassette that Stan accidentally dropped in 1970. And guns are easy to get because Stan neglected to shoot Brady, thus no Brady Bill.
Subverted in the Fantastic Four 2007 animated series episode "Out of Time". While the Four are on a field trip to prehistoric Earth the Thing swats a mosquito, just as Mr Fantastic warns them not to change anything. The camera then pulls back to show he's already killed a dinosaur. Reed later assures him that this can't possibly have had the effect of Dr Doom ruling the world. But when the Torch gives cavemen the secret of fire, he's worshiped as a god in modern New York (although In Spite of a Nail, 15,000 years of Johnny Storm worship hasn't changed anything except the Statue of Liberty).
Everyone in New York chanting Johnny's name doesn't count?
Justice League, "A Better World" has an alternate universe where the League is a group of "well-intentioned" extremists, set off by the nail being the death of their Flash. Implications of this episode would face the main continuity for nearly the remainder of the show.
Beast Wars: G1 Megatron wanted to have any descendent with the possibility try this (he somehow knew he wouldn't be alive to try it himself by the time the technology that'd allow time travel would be developed enough for this), with the nail being killing G1 Optimus Prime as the original transformers slept on prehistoric Earth, in order to sway The Great War into the Decepticons' favor because of course Optimus never dies, and when he doesit's always permanent. Beast Wars Megs very reluctantly tried this once, because he likely knew had he no other options, Unicron would've likely killed everything in this time continuity.
When the timeline is restored by the Maximals and the Heel-Face Turn Blackarachnia, Megatron decides to try something a little different and goes after the primitive humans, as their help would later assure Autobot victory over the Decepticons.
Though there is still the question of if BW Megs absorbs G1 Megs Spark meaning in the "restored" timeline G1 Megatron is a sparkless shell.
He isn't. In a scene cut from the last episode, G1 Megatron is shown with his spark being restored to him. Presumably this was how he learned of the later technology that made the entire concept possible, resulting in a Stable Time Loop.
Freakazoid! inverts this. The titular hero ends up at Pearl Harbor in December 1941 and stops the Japanese from invading. When he comes back to the present, the world seems to be a better place: Sharon Stone can act, Rush Limbaugh's a "bleeding-heart liberal", EuroDisney is booming, cold fusion works, and there are no Chevy Chase movies. Just one catch: the Brain is President.
Considering he likely had a hand in a fair amount of it, how is that a catch?
The Simpsons inverts it as well by having Homer's guardian angel Werner Klemperer show Homer what his life would have been like had he not married Marge. In the alternate timeline, Homer is rich and happily married to a beautiful woman, while Marge is the President, enjoying both success and popularity. Needless to say, this was not a successful trip for the guardian angel.
In a Treehouse of Horror sketch, the Butterfly Effect is taken to ridiculous extremes as Homer keeps traveling back in time and each time he steps on something, it changes the future in wildly differing ways. He comes to a future where the family is wealthy, his sisters-in-law are dead... but no one has heard of donuts. Homer runs back in time screaming (meanwhile it is raining donuts outside) and just indiscriminately squashes whatever is around him. He comes back to find everything normal... except everyone has forked, lizard-like tongues. He shrugs: "Close enough."
In the Phineas and Ferb epsiode "Phineas and Ferb's Quantum Boogaloo", future Candace travels back in time and helps her younger self bust Phineas and Ferb on the first day of summer. When she returns to her own time, she discovers this act has lead to the tri-state area becoming a dystopia ruled by Doofenshmirtz. She then has to travel back in time again and stop herself from helping her younger self from busting her brothers.
Specifically, when Linda saw the rollercoaster, she called for someone to rescue the kids. The helicopter pilot flying nearby answered her pleas, causing Perry to miss the helicopter. Not believing the giant ball wouldn't hit the top of the building, Doofenshmirtz jumped out of the way. Perry wasn't so fast and got hit. Parental overprotectiveness reached huge levels and Doofenshmirtz offered to childproof the Tri-State Area if the people made him their ruler and Perry didn't recover from his injuries on time to stop him.
Gaia says in the intro that they are "five special young people". Apparently they're very special indeed.
A sketch on Robot Chicken that shows what would happen if jerks got a time machine. It ends with one jerk stopping Nazism from ever getting started by humiliating Hitler, thus becoming a Hero with a Time Machine.
In a parody of Popeye, an angel shows Wimpy what would have happened if he did not exist when Wimpy attempts suicide. Popeye and Brutus are friends, Olive has huge breasts, Goon gains a doctorate, there is no war, and all hamburgers are free. The angel, seeing that he failed, pushes Wimpy off the bridge.
Similar to the Popeye example, there was a Christmas Episode of Beavis and Butt-Head where an angel shows Butt-Head how life would be without him, showing things like Principal McVicker being normal and Beavis working at a soup kitchen with Stewart. Despite this, Butt-Head's influence still permeates into this universe, too.
In the Rated A for Awesome episode "Thera's Date With Destiny" Noam's new future-predicting invention shows that Thera will be going to prom with Chet. They try to change the outcome, but each attempt either has them start dating even sooner or she goes to prom with someone else she doesn't want to go with. That is until the last vision, which doesn't show her date's face, but it's hinted to be Noam. Each vision after the first also shows her with a different hairstyle.
Ultimate Book of Spells: When the Wizarding School went into a field trip to the past, Gus took a crystal as a souvenir. Unfortunately, without that crystal to power up his wand, Cassy's great-grandfather couldn't defeat Zarlak, resulting in a Bad Future where Zarlak rules. Fortunately UBOS managed to take the heroes back to the past to set things right.
The Where on Earth Is Carmen Sandiego? episode "Timing is Everything" had one of Carmen's henchmen, Mason-Dixon, go back in time and tamper with one of Carmen's first heists. After he caused her to fail at evading the police, she went on to become his discouraged henchwoman.
In the fifth season premiere of Adventure Time, Finn wishes that the Lich never existed, creating an Alternate Timeline where the Lich never came to be. Things go downhill from there very rapidly. And to top it off, the Lich is born anyway, although several years later than he would have and in a radically different form.
In the Lilo & Stitch: The Series episode "Melty", Lilo embarrasses herself in front of her crush Keoni and goes back in time to make it so it didn't happen, but her every attempt to stop it from happening makes everything far worse. In the end she fixes everything by going back and recreating the embarrassing moment.
Similar to the above entry, an episode of Jacob Two-Two had him accidentally break his older brother's Beatles record and use a time machine from his spy neighbor (seriously) to go back and fix it, but Jacob messed up something else that he had to go back and fix, etc. Ultimately, he was able to fix everything except his brother's record from being destroyed, but it turned out his neighbor had a copy anyway.
The Looney Tunes Show: In "Best Friends Redux", Daffy travels back in time to prevent Bugs from meeting his childhood best friend Rodney Rabbit. In doing so, he creates a present where Bugs never met him and no one knows who he is.
In the Danny Phantom episode Masters of All Time, Danny goes back in time to stop Jack from accidentally turning Vlad half-ghost. The result is that Jack ends up half-ghost, and Vlad and Maddie are married and living rich lives in Wisconsin. It is more or less subverted in terms of personality: Vlad is still manipulative and controlling, lying to Maddie so she would leave Jack, Maddie is still very obsessed with ghosts and in love with Jack, and Jack is still in love with her, and more or less a decent guy who unlike Vlad, did not abuse his powers for personal gain.