Living Monolith

The Living Monolith is a Marvel comics supervillain associated with the X-Men, a mutant by nature he is capable of growing to phenomenal size via absorbing cosmic energy - at the peak of his power the Living Monolith grew to the size of a planet but was unable to move as a result: however this is an extreme example of his ability.

The Living Monolith found that mutants such as Cyclops and Havoc could provide him with easy access to cosmic energy and fed off them a bit like an energy-vampire, however unlike a vampire the Living Monolith didn't need to do this to survive - he was simply extremely power hungry and sought to become a god: a fact that had been established before he became the Living Monolith when he created a cult under the name of the Living Pharaoh, where he claimed to be a messiah-figure to his followers despite his obvious goal of world-domination.

The Living Monolith also appeared as a boss in X-Men Legends II: Rise Of Apocalypse (likely due to him sharing similiar Egyptian-themes to Apocalypse, although Apocalypse far exceeds the Living Monolith in age and power).