According to the passage, who was John D. Rockfeller? He was a ______ , gave away millions.

John D. Rockfeller, the well-known millionaire, gave away millions, but he himself was very mean about small sums of money. One day he went to stay at a hotel in New York and asked for the cheapest room in it. He said, "I’m staying here alone and only need a small room." The manager showed him into a room and said, "This is our smallest and cheapest room." and added, "but why do you choose a poor room like this? When your son stays here, he always has our the most expensive room; yours is our cheapest."
   "Oh, yes," said Rockefeller, "but his father is a rich man; mine isn’t."