Although Dragon Ball had progressively been getting more dramatic with the introduction of Tao Pai Pai all the way in the Red Ribbon Army arc, the Cell arc still marked a rather jarring tonal shift for the series. The introduction of Trunks alongside the revelation that everyone in the main cast would helplessly die in his future is exceptionally dark, even for Dragon Ball.
Characters had died and the Namek arc even made genocide a plot point, but there was always an inherent optimistic running underneath Dragon Ball– no matter what happens, Goku will save the day. Future Trunks’ timeline challenges the notion that Dragon Ball will always have a happy ending– killing off every main character, one after another. It’s a miracle Future Trunks is as well adjusted as he is.
7 Son Goku
It should be noted that the manga never specifies the exact order in which the main cast die to the Artificial Humans– leaving that for the Future Trunks TV Special– but it’s made very clear in both mediums that the timeline’s problems begin when Goku dies of a Heart Virus. While fans have speculated on the virus’ origins, Trunks references it as something of a pandemic in his future.
By the time a cure has been created, Goku has long passed away. With humanity on the cusp of extinction, Trunks is tasked with going back in time to save Goku’s life and secure a better future. If not for himself, for anyone. Like Future Bulma tells her son, Goku’s mere presence lets the people around him know everything will be okay. Without Goku, the Earth is a dreary place.
6 Piccolo
It’s debatable whether Piccolo or Vegeta was stronger during the tailend of the Namek arc, but considering Piccolo would at least go head to head with second form Frieza while Vegeta (even with a Zenkai) got manhandled every time he fought the galactic tyrant, it’s perhaps safe to assume Piccolo was indeed stronger.
As a result, it makes sense he would be the first to fight the Androids. As the Dragon Balls were seemingly active at this point, Piccolo unfortunately hadn’t merged with God yet, meaning he wouldn’t be able to keep up with 17 or 18. Dragon Ball Super features a bonus chapter where Gohan & Bulma rush to gather the Dragon Balls while Piccolo holds off the Artificial Humans, but he’s ultimately killed before Gohan & Bulma can intercept Pilaf & co.
5 Vegeta
The manga doesn’t specify whether or not Vegeta had access to Super Saiyan by the time the Androids started their attack, but it’s safe to assume he did. The anime goes so far as to show Vegeta fighting back while Super Saiyan, but it ultimately isn’t enough. With Goku dead, Vegeta likely lacked his main timeline counterpart’s drive.
Similarly, Super Saiyan Vegeta was never as strong as the Androids to begin with. Even in the main timeline where Vegeta was given a three year head start, he’s utterly humiliated by Android 18. In a fight against both Androids, undoubtedly weaker even with Super Saiyan, Future Vegeta never stood a chance. Vegeta’s death marks the extinction of pureblood Saiyans in Future Trunks’ timeline.
4 Yamcha
Yamcha has one of the most interesting character arcs, if only for how hard he ends up falling on his face. At the start of the series, Yamcha is the go-to martial arts expert. He can recognize styles & stances on the fly, he has a wealth of historical knowledge in store, and his gradual growth into a competent martial artist is compelling.
Then comes the Cell arc. Being impaled by Dr. Gero formally ends Yamcha’s martial arts career. It’s a wake-up call for him that he simply can’t keep up anymore. Yamcha only barely survives thanks to a Senzu Bean, but he doesn’t see such a luxury in the future. Future Yamcha never even gets the chance to realize martial arts isn’t cut out for him anymore, dying fighting alongside Tenshinhan.
3 Tenshinhan
Believe it or not, there was once a time Tenshinhan actively played second fiddle to Goku. Both the Piccolo Daimao and 23rd Tenkaichi Budokai arcs feature Tenshinhan in a fairly important role, essentially the strongest martial artist in the cast next to Goku himself. While Tenshinhan’s importance waned with time, Toriyama held the character in enough reverence to at least honor him in the Cell and Buu arcs.
With Piccolo and Vegeta dead, Yamcha & Tenshinhan likely felt the weight of the world on their shoulders. Keep in mind they were dead while the main cast were on Namek, meaning they’d have been considerably weaker than Piccolo or Vegeta. Yamcha and Tenshinhan effectively showed up to die, but they did show up.
2 Krillin
By the time the Saiyans invaded Earth, Krillin was still weaker than Tenshinhan but not by too much. Their Battle Powers showcase that Krillin has begun to close the gap, and Tenshinhan’s death more or less paves the way for Krillin to surpass him outright. In going to Namek, Krillin has his potential unlocked and comes back to Earth much, much stronger.
It’s even suggesting he was getting stronger while fighting Frieza. By the time the Androids arrived, there’s no doubt Krillin has surpassed Tenshinhan completely, but even this wouldn’t be enough to stand in the way of the Artificial Humans. While Krillin would marry 18 in the main timeline, he’d be killed by his future wife and brother-in-law in a joint attack.
1 Son Gohan
The every member of the Dragon Team dead, Son Gohan is left to pick up the pieces and protect the Earth. To his credit, Gohan not only manages to trigger Super Saiyan seemingly himself, he actually does protect a decent chunk of civilization for years, all while training Future Trunks in the process.
Unfortunately, Future Gohan’s greatest flaw is his inability to see past his limits. Gohan has become about as strong as Goku was as a Super Saiyan on Namek, but that’s clearly not enough to fight back. Not just that, Gohan doesn’t realize there’s a way to improve upon Super Saiyan, instead seeing Trunks as his last hope. Without his father to guide him, Gohan forever lives in his shadows and can never achieve anything greater.