Keto is a character from the animated series The New Adventures of He-Man.
Keto was a large, rock-like alien who crashed into the underwater city of Serus on Primus. He planned to drain all the energy on Primus so that he and his people could continue their travels across the galaxy. He did not care that the people of Primus would be destroyed in the process.
In reality, his mission was to seek out other life forms and determine whether they posed a threat to his people. When He-Man offered to give Keto his sword if he left, Keto was impressed by his nobility and agreed to leave Primus in peace.