Is zero from borderlands 2 a robot?

Answer 1

Yes, Zer0 can talk, he'll make comments as you play, like the other characters. If you find the audio logs in Sawtooth Cauldron, you'll learn he sometimes composes a haiku after killing a target.

Answer 2

They never confirm nor deny what he is. He could be a man, machine, or alien. He has only four digits on his hands, which could be evidence pointing to mechanical replacements or a non-human origin.