You can find more information on Hollow Ichigo here on the page dedicated to him. * He has his initial Possession Form where he takes over Ichigo during his fight with Byakuya Kuchiki. * He has his first Full Hollow form which he takes on while Ichigo is training to control his inner Hollow. * He gains a New Hollow Form during Ichigo's battle with Ulquiorra Cifer. * His Hollow merges with Tensa Zangetsu while he is trying to gain the Final Getsuga Tenshō. You can find all these on his dedicated page above.