If a green man lives in a green house, a purple man lives in a purple house, a blue man lives in a blue house, a yellow man lives in a yellow house, a black man lives in a black house. Who lives in a White house?

“A white man”

The riddle is not about the color of the person but rather a play on the term 'White House', which is a well-known residence of the President of the United States.

“A ghost”

While a ghost might be associated with the color white, the riddle specifically refers to a prominent figure associated with the White House, which is the President.

“An ice cream man”

This guess is incorrect because it does not relate to the context of the riddle, which involves houses and their occupants, rather than professions or food items.