Thearon Rhoisoh

main entry for him is at Thearon
The main bad guy during the time of Desmond Harris and Jason scott-Harris. He is carrying on the legacy of his father Kai'zen, seeking revenge on Sen'tran and trying to take over the universe. 
In Desmond's time he is at ESM, but he returns to his birthplace, Rhoisoh, after killing Desmond, and then returns to ESM and HomeStation on the Marrion Jay disguised as Rhonda Teppin while it is returning Jason from D'zeron. 
He is a shape shifter, his primary form being a homanoid wildcat.
He is beheaded by Jason with Harris's light saber.
He has telepathic abilities which allow him to take control of people and make them his minions. when he dies some of his inions die, ad many of his minions disappear. Details have not been worked out, this is one of the worst holes still remaining in the story. 
I'm not very good at making up bad guys.