Bitch-Brian is the name of Brian Griffin's mentally challenged and deformed clone in Quagmire's Baby. He was created by Bitch-Stewie, because Stewie was too lazy to do so.
Bitch-Brian does not know how to use the bathroom by himself, and even asked Brian to come help him. He even once said that he sharpened a pencil in his anus and that he needed a band-aid. Because Bitch-Stewie created Bitch-Brian, he was even more defective than Bitch-Stewie, therefore far less helpful. Bitch-Stewie was able to help plan Stewie's schedule and do jobs for him, while Bitch-Brian just hindered Brian and didn't do the jobs he asked, but rather did unnecessary things like make Brian a God's eye.
Nearing the end of the episode, Bitch-Brian's jaw drops off, Bitch-Stewie breaks his leg and his eye pops out, and both of the clones soon dissolve.
Like Brian, he is voiced by Seth MacFarlane.