Zamasu

"Evil is violence like that of the Babarians and conceit like that of Son Goku, who would trade blows with the gods. Humans use their god-given wisdom for evil and spoil our beautiful world. The humans who have gained wisdom are true evil. Does this not strike you as half-hearted? What good are gods if they do not destroy evil?!"

- Zamasu to Gowasu. "Humans truly are dangerous beings. Son Goku I will not forget you."

- Zamasu after his lost against Goku. "My form is justice. My form is the world! Revere me. Praise me. The noble and beautiful, immortal and most powerful god, Zamasu!"

- Zamasu after fusing with Goku Black.

Zamasu (in Japanese: ザマス) is one of the two main antagonists in the "Future" Trunks Arc of Dragon Ball Super. He is working alongside Goku Black to kill all of the humans.

Zamasu was formerly the North Kaio of Universe 10 and the apprentice of Gowasu, the Kaioshin of Universe 10. He holds an incredibly black and white viewpoint, believing that the gods are all good, whereas humans are evil and need to be wiped out for the good of the universe.

He is voiced by Shin-ichiro Miki.

Personality
While a man who cares for the development and prosperity of the universe, the present Zamasu often questioned the worth of humanity, not trusting in their ability to handle conflict, as they were prone to commence war in a repeated cycle. He also did not agree with how the Kais would not be more directly involved in mortals' actions, like the Gods of Destruction. Despite this, he acknowledged his lack of personal experience and was willing to diligently listen to his teacher Gowasu's words. To which, he was a humble, deferential, and level-headed man with just goals, as Gowasu noted by how well-balanced he would brew tea, implying that he was a just man. In battle, he is shown to be a very calm, regular, and methodical fighter, carefully perceiving his opponent's attack style and seamlessly countering in a fluid manner.

After meeting Goku however, his views radically changed, and his distrustful nature towards humanity only grew. Annoyed at Goku's carefree attitude and lack of respect, his distaste for the gods not quelling the dangerous nature of mortals evolved to a radicalism-level. Shocked at how a mortal like Goku could gain a power rivaling gods (or even obtain such power to begin with) and so recklessly challenge one, Zamasu came to sternly believe that humanity by nature is an evil.

The future version of Zamasu, however, has truly fallen into the depths of evil, speaking of humans and of the Saiyans as "mere humans" who are inferior to him. Similar to his partner Goku Black, he has a sadistic goal of ridding the entire universe of humans in the name of "justice", believing them to be the source of all evil, and he refers to a world without them as a "utopia". Future Zamasu also seems to have a deep hatred for Goku, as he considers killing him as his main goal and something only he should do (a trait his past counterpart is slowly developing). While battling Goku and Future Trunks, he constantly speaks about how humans misuse their "god-given wisdom" for their own personal gain. Also, Future Zamasu refers to his immortal body as befitting for him.

Main Timeline
Goku first encounters Zamasu chronologically when he, Beerus and Whis go to see him and his master, Gowasu. Goku spars with Zamasu and defeats him. He offers his hand to Zamasu, but the latter refuses. Zamasu's defeat at Goku's hands would only further his hatred of mortals.

Zamasu later suggests to Gowasu that they wipe out the primitive and violent humans on Planet Babari. Gowasu, however, states that only Gods of Destruction can carry out that act. Gowasu then uses the Time Ring to allow him and Zamasu to travel to the future of Babari. He also gives Zamasu an earring that makes him a Kaioshin, as apprentices cannot go.

The two fist bump and say "1000 years", transporting them to the future of Babari, where the planet's natives are fighting each other. This only serves to further Zamasu's belief that mortals are all bad. A Babari attacks the two, but Zamasu slices it in half, against Gowasu's wishes.

Returning to the future, Zamasu returns the earring Gowasu loaned him and debates his master on whether they can learn from mortals.

The Future Zamasu later appears in Future Trunks's timeline, wearing a green earring instead of a pair of orange ones, giving him the rank of Supreme Kai. Zamasu stopped Goku Black from using his Kamehameha, reminding Black of his promise to allow him to kill Goku. He then engages Goku in combat along with Goku Black. Future Trunks aids Goku in his fight, Goku fought Black and Trunks fought Zamasu. Goku is overpowered by Goku Black and Trunks manages to stab Zamasu but his wound healed (due to having an immortal body). He then holds down both Goku and Trunks so that Black's Kamehameha blast can hit them. With Goku, Future Trunks, and Vegeta defeated by the duo, the Resistance saves them and then the three of them flee to the past. Goku Black is angered but Zamasu then says that they will return.

Back in the present timeline, Present day Zamasu gets Gowasu some tea. Gowasu is watching the fight between Goku and Hit on GodTube. Zamasu sees the Super Dragon Balls on the monitor and asks Gowasu what they are. When he got his answer he became interested in the wish orbs. He then arrives in Zuno's place in Universe 7 and asks him about the Super Dragon Ball's and Son Goku.

Zamasu later tries to kill Gowasu and steal his time ring, but his attempt is foiled by the arrival of Goku, Beerus, Whis and the Universe 7 Kaioshin. Whis then reveals Zamasu's true plan to Gowasu. Zamasu then attempts to attack Goku, but his attack is blocked by Beerus, who disintegrates him.

However, this does not put an end to Future Zamasu, who is still working with Black in the future. When Goku, Trunks, Vegeta and Bulma traveled to the future, he and Black detected the former three's ki and went to confront them. There, Black revealed his origins to the Saiyans and two battle them, forcing Goku Vegeta and Bulma to retreat while Trunks holds the two Kaioshin off.

Goku and his friends later return, having learned the Mafuba technique to contain Zamasu. However, Goku Black distracts Goku and Vegeta with his newfound power, forcing Trunks to learn the technique in just a few minutes. To buy time for Trunks to practice the technique, Bulma attempts to distract Zamasu by seducing him. However, Zamasu is not amused, and quickly casts Bulma aside.

Before Zamasu can kill Bulma, Trunks and Mai arrive, and Trunks uses the Mafuba to seal Zamasu in a pot. However, the three then realize Bulma forgot the seal to place on the pot, allowing Zamasu to break free. Sensing something wrong with Zamasu's energy, Goku Black goes to see what's going wrong. The two then fuse, with Zamasu proclaiming himself to be the most powerful god.

Alternate Timeline
An alternate Zamasu managed to kill Gowasu and steal a Time Ring, allowing him go to an alternate future, kill the Gowasu there and team up with his alternate counterpart. Prior to this, Zamasu used the Time Ring to travel to when the Super Dragon Balls were usable, and wish to switch bodies with Goku. This Zamasu would later come to be known as Goku Black.

Goku Black then traveled to Future Zamasu's timeline, killed the Gowasu their and teamed up with Future Zamasu. They then used the Time Rings to travel to when the Super Dragon Balls were usable and used them to give Future Zamasu an immortal body. With their newfound power, the duo exterminated all of the Gods in Future Trunks's timeline and destroyed the Super Dragon Balls so they could never be used to undo their actions.

Powers and Abilites
According to Goku, Zamasu's power surpasses the power of Universe 7's Kaioshin, though he is not as strong as Super Saiyan Goku.

His future counterpart can fight on par with Super Saiyan Blue Goku when he is at full power, as well as stand his ground against Super Saiyan 2 Future Trunks. Zamasu also share a similar ki signature with his partner in crime, Goku Black.

Trivia

 * Zamasu is very similar to the Christian Devil: as he was a creature of the sky became evil because of his desire considered wrong by his master.