Lizan is a Human arms dealer.
He sold Bak'al the explosives that were used to bomb the summit at Dar Eshkalon. When Teal'c discovered this, he tortured him to learn the location of Bak'al. He later returned to demand the location of Arkad and presumably got it as he attacked Arkad after meeting Lizan. He was unsympathetic towards the Jaffa in their state of civil war because they had conquered and enslaved many other peoples while in the service of the Goa'uld. (SG1: "Talion")