Unlike its contemporaries that, on some level, ground themselves in continuity, American Dad! fully embraces the inherent fantasy of animation to live in a world without consequences. While it would be easy to follow in Looney Tunes' footsteps and just have characters survive massive explosions & pitfalls with impunity, American Dad! has a much more elegant answer to its zaniness.
Due to a variety of time travel mishaps, either magical or pseudo-scientific, American Dad!'s continuity exists in a multiverse of different, alternate timelines, allowing the actual episodesto exist within a reality of its own. This may seem like a lot for a series about a family in Virginia, but they make it work. However, within the few realities where they don't, things have gone horribly, horribly wrong.
10 The Perfect Family Timeline
This one may not seem like a dark timeline, but it's uncomfortable just seeing the house with different interior paint. In "Dreaming Of A White Porsche Christmas," Stan switches lives with Principal Lewis by wishing on an ornamental, Christmas angel.
When he does, he feels the dreary consequences of no longer having his family & the inherent emptiness of the bachelor life, and wishes for his life to go back to normal. Unfortunately for him, he gets his wish. Francine, Hayley, and Steve were apparently part of some cosmic curse to punish Stan, and when he makes his last wish, he returns to his original, perfect family that is the furthest thing from the misfits that fans had come to love.
9 The Popular Steve Timeline
Only half of this timeline is actually dark, but it certainly carries enough misery to cover multiple lives. In "The Unincludeds," Steve and Snot decide to host a party for all of the unpopular kids in defiance of all of their bullying. Unbeknownst to them, this is because their school bully had grown jealous of their massive success in the future and went back in time to make them "peak" early.
While Steve and Snot catch on early, Steve finds it difficult to avoid the popular life. As he does, he finds his future self becoming increasingly hipper and more muscular, whereas Snot's future self only becomes more and more miserable, somehow even turning into a tortoise in one future.
8 The Timeline Where Klaus Leaves
If it weren't for the fact that he's an active part of the family, Klaus likely would've gone the way of Reggie the Koala and been phased out. However, in "No Weddings and a Funeral," Klaus shows everyone what a world without him looks like. After getting fed up with all of the Smith's constant harassment of him, Klaus finally decides to leave for good.
When he does, the family becomes increasingly distant. Stan and Francine divorce, leaving Stan a shell of his former shell and Francine to marry Toshi. Steve becomes a wealthy, tech leader who pleasures himself with his robots. Hayley and Jeff start a massive family with one really weird kid. Klaus didn't do much better, and it isn't until his "funeral" that everyone would realize how important he really was.
7 The Killer Hot Tub Timeline
The episode, "Hot Water," doesn't explicitly take place in an alternate reality, but given that the Smiths are alive in the next episode, it definitely didn't have any long-spanning consequences. In it, Stan becomes seduced by the alluring powers and devilish song of an evil hot tub, played by CeeLo Green.
While the family initially enjoys the hot tub lifestyle, Stan finds it increasingly difficult to leave the hot tub's side, going as far as to host a seedy party while the family was away. Things only snowball from there, as the hot tub splits the Smiths apart and then threatens them with its deathly tubes and hoses.
6 The Monkey Uprising Timeline
"In The Longest Distance Relationship," the series explores how trying and toxic a long-distance relationship can really get. Hayley has nearly gotten over the fact that Roger sent Jeff to space, and when she meets the illustrious "Millionaire" Matt Davis, she primes herself to find love again.
However, Steve's newly-found CB Radio is somehow able to tap into Jeff's spaceship and the two begin conversing again. Falling back into her hope, Hayley waits for Jeff until old age. In the distant future, Jeff returns after using a wormhole, only to find that Hayley had lived a lonely, desperate life. To make matters worse, a monkey uprising ensues, seemingly wiping out the human world. Wanting to make amends, Jeff goes back through the wormhole to make things better.
5 The Soviet Union Timeline
American Dad! may very well have the most interesting reason for an alternate world where the Soviet Union wins the Cold War. Because Stan finds that Liberal culture has diluted his traditional take on Christmas, the Ghost of Christmas Past tries to teach him a lesson, only to allow him to run off to kill Jane Fonda.
Because of time travel shenanigans, Stan ends up meeting with Martin Scorsese, preventing him from ever doing drugs and thus preventing him from creating Taxi Driver. Because John Hinckley, Jr. wasn't able to see Jodie Foster in the movie, he didn't go insane and try to assassinate Ronald Reagan. This would lead to Walter Mondale winning the 1984 election and, thus, surrendering the U.S. to the Soviets. Taxi Driver was apparently a really important movie.
4 The Golden Turd Timeline
The golden turd has been one of the series' most beloved and intense recurring gags. After Roger gets stomach troubles from a burrito, he poops out a golden turd that for years has been corrupting anyone and everyone that's seen it. While this has resulted in a variety of horrific events, its ultimate conclusion came in the series' 300th episode.
When the golden turd is finally returned to Roger's body, he breaks apart and the entire world finds peace. Growing bored of that world, the Smiths decide to piece Roger back together but, in the aftermath, fall prey to the golden turd. This leads to a distant future where the Smiths have been hunting each other for years. On a cold night, their greed leads them to kill one another in a passionate haze.
3 The 200 Timeline
In the series' 200th episode, "The Two Hundred," Roger accidentally destroys civilization when he crawls into a hadron collider. This would release all of his personas who would go on to ravage the world as "The Two Hundred." With society pushed off the edge, several people have turned to hiding, others resorted to cannibalism, and the Smiths are separated once again.
After traversing the apocalyptic hellscape, Stan, after pushing away his family, eventually reunites with them only to fall into the middle of a grand battle between the maddened survivors and the Rogers.
2 The E-Sport Timeline
This one isn't exactly a traditional timeline in the sense that it takes place in another dimension, but it does portray a different course of causality. Stan starts having some father-son time with Steve, but when work calls, he ends things abruptly for his next mission.
Because a North Korean General is going to attend an Overwatch tournament in Hong Kong, Stan asks Steve to coach him and his CIA buddies to rise through the tournament. They would sadly fail at their attempt, sparking a nuclear battle between the U.S. and North Korea that inevitably destroyed the world.
1 The Rapture Timeline
The Rapture timeline is by far the darkest timeline in the series. On Christmas Day, the Rapture finally hits the world and leaves Stan and Francine on Earth. After Stan abandons Francine, Francine would go on to date Jesus Christ when he returns to lead God's army. Seven years later, the world is an apocalyptic landscape.
Demons are running amok, the battle is nearing its end, and Stan now travels the world as a hardened, lone warrior. When the Antichrist kidnaps Francine, Jesus and Stan must team up to save her and save the world. One of them doesn't leave alive.