Few stories change as radically as Dragon Ball did over its ten year publication as a manga. What began as a light parody of Journey to the West with an emphasis on comedy & adventure gradually became a martial arts epic that could balance humor just as well as dramatic character work– along with some of the best fight choreography seen in the medium. Over time, Dragon Ball would introduce Ki, transformations, and eventually Fusions.
Originating in the Majin Buu arc, Fusion combines two warriors together into all new characters– most of which some of the strongest in Dragon Ball. Naturally, fusion is overpowered enough where the series doesn’t rely on it too often, but Dragon Ball Super has recently made a habit of reintroducing Fusion back into the fold.
8 Gotenks
Goku spends seven years in the afterlife following the events of the Cell Games, learning from the world’s greatest dead martial artists. Goku not only triggers Super Saiyan 3 during this time, he also learns the Metamoran Fusion, a dance which fuses two martial artists of similar Battle Power into the same warrior.
Goku ends up teaching this technique to Goten and Trunks in hopes that they’ll be able to defeat Majin Buu in his stead. While Gotenks is supremely powerful– ultimately stronger than even Super Saiyan 3 Goku as a basic Super Saiyan– he’s too immature and inexperienced to finish Buu off during any of their fights.
7 Rou Kaioshin
After Vegeta and Goku end up using enough energy to wake up Majin Buu, Gohan and Kaioshin are left at the Djinn’s mercy. Gohan nearly dies in the aftermath, Kaioshin finding him just in time to whisk him away to his planet. There, Gohan trains with the legendary Z Sword, what Kaioshin believes to be their only chance at defeating Buu.
What they don’t know is that the Rou Kaioshin lurks within the blade, a Kaioshin who fused with a Witch eons ago through Potara Fusion– a (then) permanent method of fusion where the two participants are drawn together via the Potara earrings. This has seemingly only made the Rou Kaioshin more powerful, however, as he’s able to unlock all of Gohan’s latent potential.
6 Kibitoshin
Ultimate Gohan might be the strongest unfused character by the end of Dragon Ball, but he doesn’t manage to defeat Majin Buu himself. Buu absorbs both Gotenks and Piccolo before Gohan gets the chance, resulting in a one-sided fight Gohan can’t recover from. Recognizing the high stakes of the situation, Rou Kaioshin gives his life so Goku can return to Earth.
But noth without revealing that he and Gohan can fuse together via the Potara earrings. As a demonstration, Kaioshin and Kibito fuse together– albeit before Rou Kaioshin can explain that they’ll be stuck together forever. Kibitoshin is thus born and he remains as such throughout Dragon Ball GT. Super curiously defuses the two following Battle of Gods.
5 Vegetto
While Goku makes it back to Earth in time to throw Gohan his half of the Potara, Gohan misses the catch and gets absorbed by Majin Buu as a result. With no options left, Goku considers fusing with Mr. Satan or Dende before Vegeta appears. Vegeta puts up resistance at first, but Goku convinces his rival to merge with him.
The two Saiyans become Vegetto, the single strongest character in the original Dragon Ball. Fueled by Goku and Vegeta’s rivalry, Vegetto is even stronger than he otherwise would be, utterly humiliating Buuhan during their battle. Vegetto’s plan isn’t to defeat the Djinn, however, but to be absorbed himself and rescue the supporting cast.
4 Aka
Yo! Son Goku and His Friends Return!! was a 2008 short film set between the end of the Majin Buu arc and the end of the original series. Son Goku and His Friends Return is a rather lighthearted reunion special that focuses more on the heart of Dragon Ball instead of action.
That said, remnants of the Frieza Force arrive to wreak havoc. Abo and Kado fuse together into Aka, but they’re not anywhere near strong enough to prompt Goku into action. Goten and Trunks fuse into Gotenks, more than enough to put Aka in his place.
3 Merged Zamasu
The Goku Black arc is a change of pace for Dragon Ball Super, and arguably the point where the sequel series started to grow its legs. Along with reintroducing Future Trunks into the mold, the main villain is Goku Black– a Kaioshin who stole Goku’s body in his plan to wipe out all mortals in the multiverse.
Goku Black ends up enlisting his own help from an alternate timeline where he was still the Kaioshin Zamasu, and the two ultimately fuse together via the Potara earrings. As Zamasu had previously wished for immortality, Merged Zamasu is an unkillable being who can’t defuse and requires Zeno erasing the entire multiverse just to subdue.
2 Kefla
Caulifla and Kale are two of Universe 6’s strongest fighters, along with U6’s only real chance at victory in the Tournament of Power once Hit is eliminated by Jiren. While Caulifla and Kale aren’t strong enough on their own to secure victory, they’re both quick learners who tap into new forms of Super Saiyan throughout the course of the tournament.
Eventually, they’re forced to fuse into Kefla, a move Zeno approves of due to its pazazz. In the anime, Kefla squares off against Ultra Instinct -Sign- Goku in one of Dragon Ball Super’s best fights, whereas she fights Gohan in the manga in a condensed, albeit still engaging, battle.
1 Gogeta
Originally debuting in the non-canon Fusion Reborn, Gogeta made his first canon appearance in Dragon Ball Super: Broly. Unable to defeat Broly themselves, Goku and Vegeta perform Metamoran Fusion in order to become Gogeta. Absurdly powerful, Gogeta doesn’t so much as break a sweat against Broly.
For every tier in power Broly increases, Gogeta taps into a new level of Super Saiyan, finishing things off in Super Saiyan Blue. Unlike other instances of overpowered fusions in Dragon Ball, Gogeta doesn’t waste so much time that he defuses. Gogeta even had time to spare to chat with Frieza after the fact.