The Black Tiger was a Web Spinner that had undergone excessive mutation, increasing its size three to six times that of normal Web Spinners due to prolonged infection of the t-Virus. Also, unlike the ironically named Web Spinner, it was actually capable of producing a web.
Due to the Web Spinners' unpredictable nature, B.O.W. research on the specimens was suspended, and the subjects supposedly destroyed. This specimen had an unusual reaction to the virus, becoming a larger and more-deadly version. With the mansion compromised by a t-Virus outbreak, the spider population was no longer controlled. This allowed the Black Tiger to reside with its Web Spinner siblings in the underground caverns below the courtyard. It was killed by the S.T.A.R.S. Alpha team during the Mansion Incident.