Sylth Vester wears a large suit of cyborg body armor, which covers various injuries inflicted by his previous encounters with Tweetums. Among his known injuries are:
- His back teeth being pulled out.
- A lack of fur on his belly from being dipped in molecular acid.
- An injured arm from getting stuck in a particle accelerator.
- A severely disfigured face from being sucked into a black hole.
Sylth Vester works for Queen Grannicus in her plot to prevent the Royal Tweetums from reclaiming the throne. Both were defeated in the end.
When Optimatus invaded Blanc, the Loonatics freed Sylth Vester so he could help them find Tweetums. He also helped them in stopping Optimatus and Deuce's plan to rule the universe, although in the end, he was arrested by Tweetums for telling Deuce how to use the scepter. Since he helped the Loonatics save the universe, it indicates that he is also able to do good. He sometimes says "Sufferin Succotash" just like like Sylvester.
Sylth Vester is a fierce warrior, and is practically unstoppable in hand-to-hand combat.
His name is an amalgamation of "Sylvester", "Sith" and "Darth Vader" (who was a Sith lord).
Sylth Vester's body seems to be heavily augmented to help support his body after his encounters with Tweetums, similar to Anakin Skywalker when he became Darth Vader. In the episode "Fall of Blanc, Part I", for a split second right after Slam freed from his prison cell, he is able to duck his head into his armor. This implies his entire body might be just a robotic suit.