[2] Berryman was born with hypohidrotic ectodermal dysplasia, a rare condition characterized by the absence of sweat glands, hair, and fingernails; his unusual physical appearance has allowed Berryman to make a career out of portraying characters in a number of cult films, horror films and B movies.

He has appeared in a wide range of feature films and television series, including Star Trek, The X-Files, and Highway to Heaven, in which he portrayed Satan.

[5] Berryman's mother was a nurse, and his father was a U.S. Navy neurosurgeon[1] who was deployed to the Hiroshima fallout zone in the wake of the atomic bombing.

[6] Berryman was born with hypohidrotic ectodermal dysplasia, a rare genetic condition that affects the development of sweat glands, skin, hair, and fingernails.

[4] After completing high school, Berryman attended California Polytechnic State University, San Luis Obispo, where he studied botany and zoology.

[2] His time on set for The Hills Have Eyes proved difficult for him, since, during the 4-month shoot, temperatures in the desert routinely surpassed 100 degrees Fahrenheit and, without sweat glands, he had to take special precautions to avoid suffering heatstroke.