Still treating me like dirt, eh, George?. Well enjoy it while you can. Because I'm going to destroy your world the way you ruined mine.
~ Rovi declaring revenge on George

Rovi Grubelddim is the main antagonist of the My Hero episode "Nemesis".

He is a Ultroian who was a schoolmate of George Sunday (who later became Thermoman), who would flick Rovi's ears (due to sitting behind in class) and beat him at anything. At one point, Rovi had a twelve eyed girlfriend named Matilda, who later left him for George.

Years later, at a school reunion in Croydon in England, Rovi once again encountered George, who was attending the reunion with his girlfriend Janet Dawkins. Rovi revealed that since school, he has been elected to the regional branch of the High Council, but it wasn't easy as he worked hard in Galaxy Administration for 15 years. After George and Janet leave, Rovi believes that his former schoolmate is still treating him like dirt and declares vengeance on him.

Some short time later, Rovi went to George's health food shop in Northolt and told his assistant Tyler that he is a friend of George and knew him before he was Thermoman. He asked Tyler if George had any weaknesses, to which Tyler said Walnut Whips. When George arrives back from another mission as Thermoman, Rovi disguises himself as a box of dried apricots and overheard George telling Tyler about Dr. Piers Crispin's attempts to steal Janet from him.

Rovi went to the Northolt Health Centre and went to Piers and revealed his Ultroian origins to him by melting a doorknob with his breath. He then told Piers that the Ultron Council were far from happy about Thermoman and believed that Earth deserved a homegrown superhero. Rovi offered Piers a superpower called Superattraction, which would make him irresistible. Rovi then went inside Piers' body and took control of him, though Piers would give some resistance.

Due to Superattraction, Janet became attracted to Piers (unaware of what had happened) and witnessed him show off his powers. Thermoman was alerted of what was going on and was told by Rovi through Piers that some people on the Council thought he wasn't cutting the mustard and that he (Piers) would be looking after the world from now on. When becoming a superhero, Rovi/Piers took the name of Miracle Man and invited Janet for a date to which she declined and went outside the health centre. Miracle Man followed her and made a car head for her, giving him an opportunity to save her and kiss her, just as Thermoman arrived and watch on in shock and jealously.

After encouragement from Tyler, George decided to confront Miracle Man and discovered that it was Rovi controlling Piers all along. Rovi declared that he was getting revenge on George for stealing Matilda from him, for beating him at everything and for having a better body and personality. Rovi then said that he would destroy the whole world and everyone on it (apart from Britney Spears). George then challenged Rovi for a game of Chang-Ching (Rock, Paper, Scissors) to defeat him.

Later at a warehouse, whilst being watched on by Janet and George's cousin Arnie, George and Miracle Man started the game with Rovi winning the first round and George winning the second. Before going onto the third and final round, George went to Janet and kissed her and slipped her an antidote to Superattraction, which causes her to see Rovi inside Piers. For the final round, Rovi chose scissors whilst George initially chose paper, but Janet signalled him to chose rock instead, which he does. After losing to George, Rovi left Piers' body and seemly exploded, leaving Piers standing naked asking if what is happening is a dream (perhaps hinting that the Miracle Man suit was connected to Rovi).