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.
Sentry (Kree) Sentry-459 is a fictional character appearing in American comic books published by Marvel Comics. It is one of series of giant humanoid robots called Kree Sentries built by the Kree.