Most of my comic books are reference heavy, not just on objects and places, but also human characters. In Transformers, Autobots have this "holo-driver" that reflects the persona of each of their counter parts. Simon would write a brief discription of what the driver looks like, and I would find a real life actor or famous individual to "play" this part. I don't like to shoot for exact look of the say actor, but rather the characteristic and hopefully capture his or her personality.
One of the holo-driver that really took everyone by surprise is Bumblebee. I was surprised to find female Bumblebee holo-driver myself. Simon really put a nice spin on this one I think. It also got me thinking, what if Bumblebee was a fan of Herbie? maybe it's why he picked the classic alternate mode? then it makes perfect sense for Bumblebee to project his driver as the driver of Herbie. At the end, I decided to based Bumblebee's holo-driver loosely on the driver of Herbie on the latest Herbie movie, Lindsay Lohan.
and you may wonder who protraits the role of Optimus Prime's driver. The answer is Ulysses S. Grant.