The Yawn was a snake-based B.O.W. that lurked around in the Spencer Mansion. It was nicknamed "Yawn" by the Arklay Laboratory team in reference to the way its mouth opens before attacking, which resembled a yawn. It was one of many test subjects bred specifically as experimental B.O.W.s. The specimen escaped however, and managed to avoid recapture by the scientists in the Arklay Laboratory. It was eventually infected with the t-Virus following the leak in May 1998, and it promptly made the mansion its home, preying on any humans that happened to come across it.