"I am proud. You have completed your Mu training. There is nothing more to teach you from the holy writings. Prince Poo, I shall relay a message to you from Eternity. The evil entity that controls all wickedness is preparing for the greatest struggle of all time... The only ones who can challenge the entity are three boys and one girl. One named Ness is the leader of the four. One of the boys is you, Prince Poo. Now that you've completed your training, search out Ness at once. For all beings, for the earth herself... I pray for growth in the might of the four."
— Star Master

The Star Master, known in Japan as Ryan-Woo-Pa (リャンウーパー Ryan’ūpā), is a character in EarthBound. He first appears when Poo sets out to complete his Mu Training, and appears again after Ness's party comes up from the exit of the Pyramid in Scaraba, where he takes Poo away for special training and instruction of the powerful PSI Starstorm α, which Poo uses to defeat Master Barf upon his return. The Star Master makes a third appearance in the present version of the Cave of the Past, where he makes Poo conscious of PSI Starstorm Ω before flying off in a tornado again.

The Star Master is also the only character that appears twice in Ness's Magicant: he can be found both near where Ness enters Magicant and the boundary where the color of the ground changes and enemies appear. In both places, he tells Ness about Magicant and the Sea of Eden.