Spoilers Ahead For Dragon Ball Super

Goku Black (ゴクウブラック Gokū Burakku), also known as Zamasu (ザマス Zamasu), though usually referred to as Black, is an alternate incarnation of [Zamasu and a former North Kai and Supreme Kai apprentice serving his former master Gowasu from the unaltered main timeline within Universe 10: The Macho Universe. He serves as the main antagonist of the "Future" Trunks Saga of Dragon Ball Super.

Black visited Universe 6, went to the Super Dragon Balls from the unaltered main timeline within that universe, summoned Super Shenron from said timeline, wished to switch bodies with Goku from the unaltered main timeline within Universe 7, and Super Shenron granted Goku Black's wish. Goku Black sought to destroy all mortals alongside Future Zamasu, an alternate counterpart of him.

When he arrived to Future Trunks's timeline, he initially referred to himself as Goku. However, due to the notable style and color difference between Black and Goku's clothings, he was given the name "Goku Black" by Future Bulma and thus took the name even when he revealed his own identity.

After Goku Black's wish to switch bodies with Goku from the unaltered main timeline within Universe 7 was granted by Super Shenron from the unaltered main timeline within Universe 6, the Saiyan body underwent some physical changes. While Goku Black is still essentially identical, he has a slightly darker skin tone and more "defined" eyes, along with a somewhat skinnier physique. His hair is also a noticeably dark shade of black with only four front spikes and three back ones. While initially wearing his Supreme Kai attire, he soon after his wish to switch bodies with the Saiyan was granted began wearing a dark grey vest, a long-sleeved black undershirt with a turtleneck, a red sash, black pants and pointy white boots. He also gave the right Potara earring to his future counterpart while still wearing the other earring on his left ear.

Goku Black initially had all the power of Goku, but did not know how to properly use it. He instead relyied on his original fighting style and natural aptitude for Divine Ki. After fighting Goku several times, he began to copy his moves and techniques and integrating them into his own fighting style. This includes Goku's Fighting Stance, the Kamehameha, Instant Transmission, and most notably the Super Saiyan transformation. Due to the fact Zamasu already knew how to use Divine Ki, when he gained the power to transform into a Super Saiyan, he was able to create a brand new transformation: Super Saiyan Rosé which was powerful enough to go toe-to-toe with Goku and Vegeta's Super Saiyan God Super Saiyan aka, Super Saiyan Blue.

Goku Black also appears as the Crimson-Masked Saiyan in Dragon Ball Heroes.