Just as John Constantine was modelled on Sting and Clark Kent's appearance was inspired by Harold Lloyd, Iron Man was also based on a real-life person.
Billionaire-industrialist and notorious recluse Howard Hughes was the blueprint for Tony Stark, and it's easy to see which elements of the business magnate found their way into the character, from his lust for invention, to his lust for the ladies.
Iron Man co-creator Stan Lee once described Hughes as follows...
"Howard Hughes was one of the most colourful men of our time. He was an inventor, an adventurer, a ladies' man and finally a nutcase. Without being crazy, [Iron Man] was Howard Hughes."
It seems only fitting that Tony Stark's father - who made his comic book debut in 1970's Iron Man #28 - is named Howard.