"Tell me, does a person become your friend, just because you introduce yourself to him? No."
http://bleachfanfiction.wikia.com/wiki/Template:Character_%28Kaiser%29 Hollow Ichigo (虚 (ホロウ) 一護, Horō Ichigo), more properly called The Hollow within Ichigo's conscience (一護 の 內面 (なぃめん) の 虚 (ホロウ), Ichigo no naimen no Horō), is a powerful entity that was created when Ichigo Kurosaki, a Shinigami, developed a Hollow inside his soul (during his near Hollowfication as a Plus), a commonality among the Vizard. Among Bleach's most prominent antagonists, the Hollow is the longest-running villain in Bleach history, randomly appearing in almost every single story arc, including the anime-only Bount, Captain Amagai and Zanpakutō Unknown Tales arcs.
He was also the central antagonist in the Arrancar arc, alongside Grimmjow Jaegerjaquez and Ulquiorra Cifer. He does not, however, effect the entire Bleach world—just Ichigo internally. His presence can also be felt throughout the Hueco Mundo and Captain Amagai arcs whenever Ichigo dons his inner Hollow's mask to fight tough opponents like the Espada. He had disappeared after Ichigo defeated him in his Inner world. Hollow Ichigo will most likely return soon as he said that if Ichigo wanted to control his power then he should not die before he shows up again.
In Bleach Shikkyakuhoshi, he has been apparently released into the real world by unknown means. He seems to have gained the ability to release both Zanpakutō spirits and Inner Hollows from one's heart. How he gained this power, or his motives are still unknown. He is the central antagonist of Bleach Shikkyakuhoshi.
He has an appearnce much fimiliar to anybody who actully watches the anime , he has the exact same clothes as ichigo's shinigami form except that the colours are flipped as ichigo wears a black robe his hollow form wears a white robe .