Giant lizard creature

The giant lizard creature is a large lizard-like creature with enormous teeth and claws who inhabits a SHU cell. The creature has an extreme sensitivity to light which is why there's tinted glass shielding the lamps in its' cell and is also extremely vicious.

John Druitt kidnaps Ashley Magnus and imprisons her in the creature's cell in an attempt to force Dr. Helen Magnus into giving him a vial of her blood which he needed to prolong his life. While Magnus is up in her study with John, she uses her computer to lower the screens in the main lab to relay a 'message' to Bigfoot, Henry Foss, and Dr. Will Zimmerman that Ashley is in mortal danger. Ashley tries to run up the enclosure wall and kick off a protective light filter, but the creature takes a swipe at her, knocking her down, then swipes again, slashing her throat.

As Magnus deals with Druitt, the three men make their way to the creature's enclosure and as Will and Bigfoot enter, Will sends Henry to go get Magnus. While Bigfoot tries and fails to control the creature with a hands-on approach, getting injured in the process, Will is able to use a loose pipe to knock off the tinted glass covering for the light Ashley had previously kicked, forcing the creature to retreat into the back of the cell long enough for Magnus and Henry to arrive to evacuate the three of them from the cell before the creature potentially killed them.