|Occupation||Supreme God (Former)|
|Debut||Chapter 108 (Skull)|
Chapter 184 (Fully)
Tathagata is large enough to dwarf the moon. He has light brown skin, white eyes with no pupils, enlongated earlobes with large golden rings around each ear, and wears a blue colored robe around his body.
Not much is shown about the God, other than being disappointed for Sun Wukong's failing his last test and unable to erase his corrupt nature, even after Sun Wukong becomes a Buddha.
He did, however, shown to be smiling when he sees Sun Wukong's rage over Tang Xuanzang's death, hinting cruelty. 
Tathagata had fought against Sun Wukong, which ends up with Sun Wukong losing.
100 years ago, it was shown that Tathagata was displeased with the Monkey King for failing his last test after wandering around India and become Buddha. He began his rematch with the Monkey King and eventually killed in the battle.
Not much is known of his abilities other than the fact that he managed to severely damage Sun Wukong before dying himself. The other gods are also confident in his abilities. At one point during his youth, The King claimed that his defeat means the defeat of the gods. As the supreme god, a being that stands above his species, he is one of the most powerful god of his time.
Odin revealed that Tathagata was much more powerful than the Monkey King. The Monkey King too acknowledged this and had to devour his master, Tang Xuanzang, to increase his power and defeat the supreme god.
Curiously, LINE translation changes Buddha's speech radically between chapters.
"You (Sun Wukong) could have become Buddha if you finished your journey to India...But you failed on your last test. After all, your rotten nature can't be saved.. You broke taboo and your sin is huge"
-Tathagata before fighting Sun Wukong in chapter 184-
"After wandering around the entire India.. And even being able to become a Buddha yourself.. You(Sun Wukong) ended up failing the final test...Ultimately, You can't erase your corrupt nature... The punishment of the taboo you violated will be great"
-Tathagata, before fighting Sun Wukong in chapter 304-