In the fictional Bleach manga/anime universe, a Hollow (虚(ホロウ, horō) is a kind of monstrous lost soul who can harm both ghosts and humans. Many of the series' antagonists are hollows. There are also hollows with Soul Reaper (a death-related entity)-like characteristics called arrancars (破面(アランカル), arankaru, from Spanish arrancar "to tear off," kanji translates as "broken mask"). One of the series' main storylines has Sōsuke Aizen (the primary antagonist for the majority of the series) and his arrancar (particularly the ten Espadas, the strongest ones) as the force opposing the protagonists.