Yawn

The Yawn was a giant snake mutated as a result of genetic tampering and a dose of the T-Virus for good measure, the Yawn was created within the Spencer Estate laboratories by researchers working for Umbrella, Inc. as a bio-weapon. Its name come from the fact it always appears to be yawning before biting its prey. The Yawn first appeared in the attic of the mansion, where it savagely bit mortally injured Richard Aiken before being driven off by Chris Redfield and Jill Valentine. When they faced the gigantic snake a second time, they finally succeeded in killing it.