James Fraser, and "B.D." himself!

Black Diamond was not a ?model? model!... Legend has it that James Fraser picked Black Diamond, a buffalo who lived in New York's Bronx Zoo, as the model for the nickel he was designing. You'd think BD would be honored, but he refused to pose! He kept turning to watch Fraser draw instead of standing sideways. Fraser had to get a zookeeper to catch the animal's eye while Fraser snuck around for a side view.

(US Mint Fun Facts)