He is portrayed by Grant McFarland.
Lothor is an exiled evil ninja master. He arrived on Earth with an army of evil space ninjas with the intent to conquer the world and destroy all of the protecting ninja academies and their ninja masters.
Fire Rebellion Storyline
Lothor will serve as one of the three secondary antagonists along with Trixie's human version (under Siren mind control triggered by Agent Nevada) and Conrad Kellogg. He'll be assisting the Nightmare Forces.
Lothor returns after escaping the Abyss of Evil, ending up in Equestria.
Despite being a major villain, Lothor did show up after his reveal till the end in which he takes Catherine Carter captive after her defeat. He takes her to his ship, give her a coller, which makes it so she can't use her psychic powers. The reason he took her is so he can find out what she knows regarding time travel.