Tony Burton, who played a tough-talking boxing trainer in six of the “Rocky” movies with Sylvester Stallone, died on Thursday in a California hospital, his family said. He was 78.

The cause was complications of pneumonia, Aurelian Burton, his wife of 36 years, said.

She said that her husband had been in and out of the hospital recently with various ailments. Mr. Burton’s daughter, Juanita, said he was suffering from dementia.

In the “Rocky” franchise, Mr. Burton portrayed Duke, the hard-as-nails trainer of the boxer Apollo Creed, Rocky’s initial nemesis and eventual best friend. He later trained Rocky himself.