There is debate as to whether or not Mother Hydra is a lesser Great Old One or merely a grotesquely mutated Deep One - though the latter seems more likely as she doesn't seem to show much in the way of supernatural power outside her gigantic size and unnaturally long life span.
Mother Hydra also acted as the main antagonist and final boss of the video-game Cthulhu: Dark Corners of The Earth. She is in a large room with an energy shield around her and groups of Deep Ones defending her. To beat her, the player must take control of a Deep One through psychic powers and flip switches to shut off her shield. They can then use the powerful Yithian Energy Cannon to electrocute her to death.