Give him a medium low voice and make it rough. The scratchier the better in all honesty.

(Copied from Wikipedia)

Viral (ヴィラル) (pronounced "Veer-ral") is a member of the Human Eradication Army, who regards Kamina as a strong rival since losing his Enki's helmet to the newly created Gurren Lagann. Though being among the more humanoid of the Beastmen, his DNA contains aspects of tiger genetics. He is extremely loyal to Lordgenome and the four supreme generals, and he does his best to serve them. He has a personal Gunmen called Enki while under General Thymilph, which mainly utilizes swords and a powerful head-mounted laser (Named in the manga as the Enki Sun Attack). After Kamina's death, he continues to fight Gurren Lagann to regain his honor, thinking that Kamina is still alive. However, upon learning the truth, a shocked Viral focuses his frustrations on Simon before refusing to kill him on Cytomander's orders when he holds Yoko hostage. Brought before Lordgenome, Viral learns the truth of the Beastmens' lifespans before receiving the gift of immortality. Though he believed it was so he can kill Simon with no fear of death in his new Gunmen Enkidudu, Lordgenome reveals that the immortality was to ensure that he had an eternal witness of the Spiral King's power. But Lordgenome dies in the battle and an astonished Viral disappears as Dekabutsu collapses around him.