The original Benji was a mixed breed of Cocker Spaniel, Poodle and Schnauzer. The original dog actor, named Higgins, was rescued from a shelter so his exact breed is unknown.

While Higgins only starred in the first Benji film, Higgins' offspring Benjean starred in many Benji movie sequels. Since Benjean was Higgins' daughter, she shared half his traits and his mixed-breed lineage. The third dog to play Benji was a distant relative of Higgins. The fourth dog to play Benji was found in a nationwide search and not related to Higgins. She was also rescued from a shelter, and her exact breed is unknown, although she displayed qualities of Cocker Spaniel and Terrier breeds.