User blog comment:GSFB/Xenomorph Queen vs Geryon/@comment-24461549-20140404230934/@comment-5232784-20140407042323

BTW: Orthrus is the two headed hound you are thinking of. A hound of Eurytion, a giant servant of Geryon, it is the brother of Cerberus, Nemean Lion and several other monsters. It had a snake for a tail and, in many if not most retellings, tiny snakes for hair. Hercules killed it too.