The Yin and the Yang of Mr. Go

Y.Y. Go

Leo Zimmerman (as Jack McGowran)

Tah-Ling

Nero Finnegan (as Jeffrey Bridges)

Prof. Robert Bannister

Zelda (as Clarissa Kaye)

The Dolphin

Dr. Ading

Ito Suzuki (as King Ho)

Parker

Dr. Yul

Miss Hagen

Clay (uncredited)

U.S. Senator (uncredited)

The uncredited voice of Gautama Buddha appears to be that of Valentine Dyall.

Y. Y. Go: Why don't I just boil away, like the green stuff on dirty water? Maybe it's because I have too much juice left. I haven't used up half my heartbeats, or any of my ambition. Maybe I've been... saving something.

Y. Y. Go: You know, Suzuki, I'm suddenly... bored with my life. Fed up with the racings of yin-yang. I've used up this air. Something has started inside me to move. You feel that way, too? Something new, strange? Something... useful. Now what could I have to do with anything useful?