He made his big screen debut at the age of four in the 1938 film Mother Carey’s Chickens. The following year, he played Peter von Frankenstein, the son of Rathbone’s Baron Wolf von Frankenstein, in Son of Frankenstein.

During filming, the young boy would often play checkers with Boris Karloff while he was in his full Frankenstein’s monster costume. Dunagan said he once won four bits off Karloff.

He was also in a scene that was cut from the 1939 film Tower of London.

It was after those roles that none other than Walt Disney himself called the family’s home in Los Angeles.

Disney wanted the young boy to “help his artist put a child’s expression on a deer,” Dunagan recalled in a 2025 interview. So his mom drove them to Disney’s Burbank studio.

The boy would go on to spend the next year of his life working on Bambi, released in 1942.

In a 2011 interview, he talked about recording the emotional scene where Bambi’s mother is shot by a hunter.

“When I was told to say, with some stress, ‘Mother … Mother,’ I must have not had the tone of fear that the story needed. A coach, I think it was a nice lady at the studio, asked me how I would cry out loud if my own real mother was lost and in great danger. That made it easy,” he said.

Bambi was his seventh and last film.

In 1952, at the age of 18, Dunagan joined the Marines. He became the youngest drill instructor in their history, and did three tours of Vietnam before retiring in 1977 as a major.

But during his military career, he kept his time as a child star under wraps.

“One of the biggest regrets of my life is that I didn’t have the courage to tell my close personal friends in the Marine Corps that I had been a part of the wonderful work of Mr. Disney,” he said.