Gus : He is a round character. Gus is more sensitive than Ben to issues of traditional human concern. He often touches upon deeper issues Ben does not wish to consider - about death, the dull routine of life, and the nature of their subtle boss, Wilson. He is concerned with the consequences of his job. But on the other part, he is unafraid to yell and peer up the dumb waiter to see his boss's face when he isn't allowed to. He is both playful and enthusiastic.
Ben : He is a flat character. Ben mostly reads his newspaper all the time, and his silences are as much a feature of his character as his dialogue. Whether Gus is asking him about the job, or if he ever gets bored with life, Ben refuses to enter into deep conversation. He is deeply violent as shown in the choking scene where he had an argument with Gus.
Wilson : He is a flat character. Wilson never appears on the stage or spoken anything, but he is directly or indirectly behind the messages from the dumb waiter and speaking through tube. He is off-stage character who plays a powerful, god-like influence over on-stage characters.