The subject of the acclaimed 1985 film Mask, he was famous for suffering from craniodiaphyseal dysplasia, a very rare bone disorder generally accompanied by severe neurological problems.
He was four years old when he was diagnosed with a rare disease that typically afflicts only one out of more than 200 million children.
The cinematic version of his life, Mask, received an Academy Award for Best Makeup Design.
His parents, Florence Tullis and Roy Dennis, Sr. suffered through the deaths of two sons: Roy passed away at age sixteen, and his brother Joshua died in his early thirties from AIDS.
Eric Stoltz portrayed Dennis in the film Mask.