Mr. William Green
Mr. Green, a civil servant, is something of a contradiction. On the one hand, he doesn't seem to think much of modern Nigeria or modern Africans. Obi thinks that Mr. Green works incredibly hard for something he doesn't even believe in. Mr. Green seems to be a tragic figure: somebody who works desperately for a country, believing in an idealized Africa that will never exist.
Mr. Green probably doesn't know what Obi thinks. In fact Mr. Green seems like the kind of boss who would take offense at Obi's assessment of him. After all, he's the one who tells Obi that if he has half a brain and isn't lazy, he'll do all-right, and then turns around and tells his African Administrative Assistant that he's there to do what he's told, not to think. Mr. Green follows this up by barking at Obi to refer to him as "sir" since he is, after all, Obi's senior. Mr. Green is certain of one thing: all Africans are corrupt. But the narrator notes that, in the end, not even Mr. Green understands why Africans like Obi are corrupt.