Towards the end of his career Johnston starred as an actor in sound motion pictures such as the popular Frankenstein films Ghost of Frankenstein and Son of Frankenstein.
Despite having been apparently killed at the end of Son of Frankenstein, Ygor was revealed only to have been "maimed by the bullets shot into him by Wolf Frankenstein".
The latter character was specifically modeled after Boris Karloff in Son of Frankenstein.
Frankenstein | James, son of Zebedee | Sanford and Son | Bride of Frankenstein | Frankenstein's monster | Son | son | Tan Son Nhut Air Base | Son of the Beach | Young Frankenstein | Parable of the Prodigal Son | Frankenstein, or The Vampire's Victim | Victor Frankenstein | Frankenstein (1931 film) | Thomas G:son | Son Volt | Son of the Morning Star | Son House | Father and Son | The Ghost of Frankenstein | Son of Rambow | Son of Frankenstein | Gamelan Son of Lion | Eason & Son | Doyle Wolfgang von Frankenstein | Thế Sơn | The Horror of Frankenstein | The Curse of Frankenstein | Son Of Cliché | Son Goku |