Ultra Magnus generally appeared as a chief lieutenant to the leader of what fictional group of sentient robots?
Optimus Prime Optimus Prime is a fictional character from the "Transformers" franchise. He is the leader of the Autobots. A fictional group of sentient robots that can transform into other forms (e.g: cars and other objects) He is the most iconic of the Transformers, being frequently featured in Popular Culture.
Dreadnought (comics) Dreadnoughts are a type of fictional robot appearing in American comic books published by Marvel Comics. They are frequently employed by villainous organizations. Different forms of the robots are depicted by organizations such as HYDRA and the Maggia.