Princess Pha is played by Miss Gloria Dea, who hails from Alameda, CA, an exotic-looking dancer who later shows up in a bit in Ed Wood's much-maligned Plan 9 From Outer Space (released 1959). King of the Kongo was Miss Dea' only leading role. But Gloria was no Miss Nobody.
She was actually Gloria Metzner, aka Gloria de Werd, and the wife of band leader slash composer Hal Borne, formerly the music director at RKO. Miss Metzner was the daughter of a stage magician and had herself started in that profession at the ripe old age of 7. She later performed in the Earl Carroll's Vanities in Hollywood and even did the Billy Rose Aquacade at the San Francisco World's Fair in 1939 opposite another screen Tarzan, Johnny Weissmuller. She disappears from entertainment news after her run-in with Ed Woods and Plan 9.
Full disclosure: The above essay was "lifted" from "Braunhart Mania," an ancestry blog run by Gloria Metzner's relative Kenneth R. Marks. I am indebted to Mr. Marks.