Vishnu

Vishnu is an Emperor-Class Honkai Beast with regenerative capabilities. Its DNA was used by Otto Apocalypse in conjunction with Kallen Kaslana's DNA to create Theresa Apocalypse, giving her his regenerative capabilities. She is shown regrowing an arm in 2nd Eruption thanks to his abilities.

According to Einstein, Vishnu is also capable of devouring other Honkai Beasts to increase its own strength. It is currently unclear if Theresa Apocalypse has an ability of a similar effect.