There is no scientific evidence to suggest that people significantly larger than the tallest normal human being ever existed. However, a condition of the pituitary gland called "agromegaly" can result in the excessive production of human growth hormone. Sufferers of agromegaly can grow to well over 8 feet in height.
Stories of giants abound in the myths and legends of many cultures. As with dragons, unicorns and other mythological creatures, there is no fossil evidence to verify the existence of giants. Stories of giant men could have been supported by the finding of large bones that appeared to be human, such as those of the prehistoric ape, "Gigantopithecus blacki," which may have grown to as much as 10 feet in height.