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.
U.S. Robots and Mechanical Men U.S. Robots and Mechanical Men, Inc. is a fictional 21st century manufacturer of robots that appears in Isaac Asimov's "Robot" series of novels and short stories.