He wasn’t supposed to live past the age of seven.

On Dec. 4, 1961, Roy L. “Rocky” Dennis was born in Glendora, California, and was initially thought to be a perfectly healthy baby. It wasn’t until an X-ray technician noticed a slight cranial anomaly when he was 18-months-old that doctors began questioning what was wrong with the adorable little boy. What started out as just a routine tonsillectomy turned into a decade-long battle for survival.

“The bridge of his nose hadn’t formed,” his mother, Florence Tullis, told the Chicago Tribune. “That happens in a lot of babies, so no one had worried much. But then his head started to grow. I went into shock.”

Rocky suffered from a rare and fatal congenital disease called craniodiaphyseal dysplasia, which caused his face and head to swell to a bizarre size and shape. Craniodiaphyseal dysplasia triggered severe headaches, paralysis, and ruptured blood vessels.

His condition was so unusual that only a handful of other cases have ever been reported. Doctors believed he would be mentally retarded, blind and dead before turning seven-years-old. But his mother, who was a former go-go dancer with a fondness for bikers and drugs, didn’t believe a word of it.

His mother insisted that her son lead as normal a life as possible. She made an effort to encourage him to do everything doctors said was impossible.

“They tried to say his intelligence was impaired, but it wasn’t true,” she told People. “I think they wanted to keep him out of the classroom because [they thought] it would bother the other kids’ parents.”

Because of his unusual appearance, the school district attempted to put Rocky away in a school for the handicapped, but Tullis raised hell and made sure he stay put.

The two of them shared an inseparable bond.

Despite his appearance, Rocky had a “happy-go-lucky attitude,” which played a huge role in helping him conquer the odds.

He even learned to accept his deformity. At one point, a plastic surgeon offered him an operation that would make him look more normal — he turned it down.

“Who will I see in the mirror if I change my face?” he asked his mother.

He may have been bullied by other kids growing up, being called “ugly,” pointed and laughed at, but ultimately, everyone grew to like him.

He became a high school honor student and graduated at the top of his class, was elected “Best Buddy,” “Most Good-Natured,” and “Friendliest Camper” at a Southern California summer camp for handicapped children. He also became a mascot at UCLA’s Center for Genetic Research, where doctors were documenting the progression of his deformation and dying.

Eventually, the headaches intensified and he was forced into a wheelchair.

When his condition became more life-threatening, Rocky started believing that when his life was over that he would be turned into another form of energy.

On Oct. 4, 1978, at the age of 16, the rare disease took his life. At his request, he died at home. His body was donated to medical science and eventually cremated.

Rocky’s life was later made into a powerful Peter Bogdanovich film in 1985 called Mask, where Eric Stoltz played a teen version of him, with Cher as his mother. In a 1986 interview, she explained how she “always thought showing Rocky’s courage would help a lot of disabled kids — and the parents of disabled kids; sometimes they are more disabled than their kids. I didn’t realize the movie would be about me, too. Thanks to Cher’s brilliance, I come off a kind of heroine.”